bitbox02/ui: inline TrinaryInputParams::to_c_params()

diff --git a/src/rust/bitbox02/src/ui/types.rs b/src/rust/bitbox02/src/ui/types.rs
index 6a16367..4bcd882 100644
--- a/src/rust/bitbox02/src/ui/types.rs
+++ b/src/rust/bitbox02/src/ui/types.rs
@@ -2,9 +2,6 @@
 
 extern crate alloc;
 use alloc::boxed::Box;
-use alloc::vec::Vec;
-
-use util::Survive;
 
 pub use bitbox02_sys::trinary_choice_t as TrinaryChoice;
 
@@ -66,40 +63,6 @@ pub struct TrinaryInputStringParams<'a> {
     pub default_to_digits: bool,
 }
 
-impl<'a> TrinaryInputStringParams<'a> {
-    #[cfg_attr(any(feature = "testing", feature = "c-unit-testing"), allow(dead_code))]
-    pub(crate) fn to_c_params(
-        &self,
-        title_scratch: &'a mut Vec<core::ffi::c_char>,
-    ) -> Survive<'a, bitbox02_sys::trinary_input_string_params_t> {
-        // We truncate at a bit higher than MAX_LABEL_SIZE, so the label component will correctly
-        // truncate and append '...'.
-        const TRUNCATE_SIZE: usize = MAX_LABEL_SIZE + 1;
-
-        *title_scratch =
-            util::strings::str_to_cstr_vec(util::strings::truncate_str(self.title, TRUNCATE_SIZE))
-                .unwrap();
-
-        Survive::new(bitbox02_sys::trinary_input_string_params_t {
-            title: title_scratch.as_ptr().cast(),
-            wordlist: match self.wordlist {
-                None => core::ptr::null(),
-                Some(wordlist) => wordlist.as_ptr(),
-            },
-            wordlist_size: match self.wordlist {
-                None => 0,
-                Some(wordlist) => wordlist.len() as _,
-            },
-            number_input: self.number_input,
-            hide: self.hide,
-            special_chars: self.special_chars,
-            longtouch: self.longtouch,
-            cancel_is_backbutton: self.cancel_is_backbutton,
-            default_to_digits: self.default_to_digits,
-        })
-    }
-}
-
 pub type SelectWordCb<'a> = Box<dyn FnMut(u8) + 'a>;
 pub type ContinueCancelCb<'a> = Box<dyn FnMut() + 'a>;
 
diff --git a/src/rust/bitbox02/src/ui/ui.rs b/src/rust/bitbox02/src/ui/ui.rs
index 87f087f..3efb699 100644
--- a/src/rust/bitbox02/src/ui/ui.rs
+++ b/src/rust/bitbox02/src/ui/ui.rs
@@ -103,10 +103,32 @@ pub async fn trinary_input_string(
         (None, core::ptr::null_mut())
     };
 
-    let mut title_scratch = Vec::new();
+    // We truncate at a bit higher than MAX_LABEL_SIZE, so the label component will correctly
+    // truncate and append '...'.
+    const TRUNCATE_SIZE: usize = super::types::MAX_LABEL_SIZE + 1;
+    let title =
+        util::strings::str_to_cstr_vec(util::strings::truncate_str(params.title, TRUNCATE_SIZE))
+            .unwrap();
+    let c_params = bitbox02_sys::trinary_input_string_params_t {
+        title: title.as_ptr().cast(),
+        wordlist: match params.wordlist {
+            None => core::ptr::null(),
+            Some(wordlist) => wordlist.as_ptr(),
+        },
+        wordlist_size: match params.wordlist {
+            None => 0,
+            Some(wordlist) => wordlist.len() as _,
+        },
+        number_input: params.number_input,
+        hide: params.hide,
+        special_chars: params.special_chars,
+        longtouch: params.longtouch,
+        cancel_is_backbutton: params.cancel_is_backbutton,
+        default_to_digits: params.default_to_digits,
+    };
     let component = unsafe {
         bitbox02_sys::trinary_input_string_create(
-            &params.to_c_params(&mut title_scratch).data, // title copied in C
+            &c_params, // title copied in C
             Some(confirm_cb),
             shared_state_ptr, // passed to confirm_cb as `user_data`.
             actual_cancel_cb,
diff --git a/src/rust/util/src/lib.rs b/src/rust/util/src/lib.rs
index bbf56da..4faa048 100644
--- a/src/rust/util/src/lib.rs
+++ b/src/rust/util/src/lib.rs
@@ -33,21 +33,6 @@ pub fn zero(dst: &mut [u8]) {
     }
 }
 
-/// Survive forces T to live at least as long as lifetme 'a.
-pub struct Survive<'a, T: 'a> {
-    pub data: T,
-    phantom: core::marker::PhantomData<&'a T>,
-}
-
-impl<T> Survive<'_, T> {
-    pub fn new(data: T) -> Self {
-        Survive {
-            data,
-            phantom: core::marker::PhantomData,
-        }
-    }
-}
-
 // # C interface
 
 /// Zero a buffer using volatile writes. Accepts null-ptr and 0-length buffers and does nothing.