[PATCH v3 4/6] rust: enable `clippy::as_ptr_cast_mut` lint

[Tamir Duberstein <tamird@gmail.com>]

In Rust 1.66.0, Clippy introduced the `as_ptr_cast_mut` lint [1]:

> Since `as_ptr` takes a `&self`, the pointer won’t have write
> permissions unless interior mutability is used, making it unlikely
> that having it as a mutable pointer is correct.

There is only one affected callsite, and the change amounts to replacing
`as _` with `.cast_mut().cast()`. This doesn't change the semantics, but
is more descriptive of what's going on.

Apply this change and enable the lint -- no functional change intended.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#as_ptr_cast_mut [1]
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
---
 Makefile              | 1 +
 rust/kernel/devres.rs | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index c62bae2b107b..bb15b86182a3 100644
--- a/Makefile
+++ b/Makefile
@@ -477,6 +477,7 @@ export rust_common_flags := --edition=2021 \
 			    -Wrust_2018_idioms \
 			    -Wunreachable_pub \
 			    -Wclippy::all \
+			    -Wclippy::as_ptr_cast_mut \
 			    -Wclippy::ignored_unit_patterns \
 			    -Wclippy::mut_mut \
 			    -Wclippy::needless_bitwise_bool \
diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
index 3a9d998ec371..598001157293 100644
--- a/rust/kernel/devres.rs
+++ b/rust/kernel/devres.rs
@@ -143,7 +143,7 @@ fn remove_action(this: &Arc<Self>) {
             bindings::devm_remove_action_nowarn(
                 this.dev.as_raw(),
                 Some(this.callback),
-                this.as_ptr() as _,
+                this.as_ptr().cast_mut().cast(),
             )
         };
 

-- 
2.48.1