rust: enable `clippy::ptr_cast_constness` lint

In Rust 1.72.0, Clippy introduced the `ptr_cast_constness` lint [1]:

> Though `as` casts between raw pointers are not terrible,
> `pointer::cast_mut` and `pointer::cast_const` are safer because they
> cannot accidentally cast the pointer to another type.

There are only 3 affected sites:
- `*mut T as *const U as *mut U` becomes `(*mut T).cast()`.
- `&self as *const Self as *mut Self` becomes
  `core::ptr::from_ref(self).cast_mut()`.
- `*const T as *mut _` becommes `(*const T).cast_mut()`.

Apply these changes and enable the lint -- no functional change
intended.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_cast_constness [1]
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250615-ptr-as-ptr-v12-2-f43b024581e8@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs
index 624d7a4c83ea..ef66deb7ce23 100644
--- a/rust/kernel/drm/device.rs
+++ b/rust/kernel/drm/device.rs
@@ -83,8 +83,8 @@ impl<T: drm::Driver> Device<T> {
         major: T::INFO.major,
         minor: T::INFO.minor,
         patchlevel: T::INFO.patchlevel,
-        name: T::INFO.name.as_char_ptr() as *mut _,
-        desc: T::INFO.desc.as_char_ptr() as *mut _,
+        name: T::INFO.name.as_char_ptr().cast_mut(),
+        desc: T::INFO.desc.as_char_ptr().cast_mut(),
 
         driver_features: drm::driver::FEAT_GEM,
         ioctls: T::IOCTLS.as_ptr(),