rust: init: replace unwraps with question mark operators

Use `?` operator in the doctests. Since it is in the examples,
using unwraps can convey a wrong impression that unwrapping is
fine in general, thus this patch removes this unwrapping.

Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/rust-for-linux/CANiq72nsK1D4NuQ1U7NqMWoYjXkqQSj4QuUEL98OmFbq022Z9A@mail.gmail.com/
Signed-off-by: Daniel Sedlak <daniel@sedlak.dev>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20241123095033.41240-2-daniel@sedlak.dev
[ Reworded commit slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: wutchzone

rust/kernel/init.rs

@@ -1076,8 +1076,9 @@ pub fn uninit<T, E>() -> impl Init<MaybeUninit<T>, E> {
 /// ```rust
 /// use kernel::{alloc::KBox, error::Error, init::init_array_from_fn};
 /// let array: KBox<[usize; 1_000]> =
-///     KBox::init::<Error>(init_array_from_fn(|i| i), GFP_KERNEL).unwrap();
+///     KBox::init::<Error>(init_array_from_fn(|i| i), GFP_KERNEL)?;
 /// assert_eq!(array.len(), 1_000);
+/// # Ok::<(), Error>(())
 /// ```
 pub fn init_array_from_fn<I, const N: usize, T, E>(
     mut make_init: impl FnMut(usize) -> I,
@@ -1120,8 +1121,9 @@ where
 /// ```rust
 /// use kernel::{sync::{Arc, Mutex}, init::pin_init_array_from_fn, new_mutex};
 /// let array: Arc<[Mutex<usize>; 1_000]> =
-///     Arc::pin_init(pin_init_array_from_fn(|i| new_mutex!(i)), GFP_KERNEL).unwrap();
+///     Arc::pin_init(pin_init_array_from_fn(|i| new_mutex!(i)), GFP_KERNEL)?;
 /// assert_eq!(array.len(), 1_000);
+/// # Ok::<(), Error>(())
 /// ```
 pub fn pin_init_array_from_fn<I, const N: usize, T, E>(
     mut make_init: impl FnMut(usize) -> I,