rust: bitfield: remove unnecessary #[allow]

The `#[allow(non_camel_case_types)]` was there because register names can
be commonly SCREAMING_CASE and thus not CamelCase. However, when a bitfield
type is created by itself, this justification does not apply. Thus, remove
it.

Users that want to use non-standard styles can add the `#[allow]`
themselves. For example, the invocation of `bitfield!` inside `register!`
macro carry this annotation.

Signed-off-by: Gary Guo <gary@garyguo.net>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://patch.msgid.link/20260910170542.92010-1-gary@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

rust/kernel/bitfield.rs

@@ -295,7 +295,6 @@ macro_rules! bitfield {
         $(#[$attr:meta])* $vis:vis struct $name:ident($storage:ty) { $($fields:tt)* }
     ) => {
         $crate::bitfield!(@core
-            #[allow(non_camel_case_types)]
             $(#[$attr])* $vis $name $storage
         );
         $crate::bitfield!(@fields $vis $name $storage { $($fields)* });