rust: bump Clippy's MSRV and clean incompatible_msrv allows

Following the Rust compiler bump, we can now update Clippy's MSRV we
set in the configuration, which will improve the diagnostics it generates.

Thus do so and clean a few of the `allow`s that are not needed anymore.

Reviewed-by: Tamir Duberstein <tamird@kernel.org>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260405235309.418950-7-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

.clippy.toml

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-msrv = "1.78.0"
+msrv = "1.85.0"
 
 check-private-items = true
 

drivers/gpu/nova-core/gsp/cmdq.rs

@@ -281,7 +281,6 @@ impl DmaGspMem {
         let (slice_1, slice_2) = {
             let (slice_1, slice_2) = self.driver_write_area();
 
-            #[allow(clippy::incompatible_msrv)]
             (slice_1.as_flattened_mut(), slice_2.as_flattened_mut())
         };
 
@@ -572,10 +571,7 @@ impl Cmdq {
             Delta::from_millis(1),
             timeout,
         )
-        .map(|(slice_1, slice_2)| {
-            #[allow(clippy::incompatible_msrv)]
-            (slice_1.as_flattened(), slice_2.as_flattened())
-        })?;
+        .map(|(slice_1, slice_2)| (slice_1.as_flattened(), slice_2.as_flattened()))?;
 
         // Extract the `GspMsgElement`.
         let (header, slice_1) = GspMsgElement::from_bytes_prefix(slice_1).ok_or(EIO)?;

rust/kernel/ptr.rs

@@ -81,7 +81,6 @@ impl Alignment {
     /// This is equivalent to [`align_of`], but with the return value provided as an [`Alignment`].
     #[inline(always)]
     pub const fn of<T>() -> Self {
-        #![allow(clippy::incompatible_msrv)]
         // This cannot panic since alignments are always powers of two.
         //
         // We unfortunately cannot use `new` as it would require the `generic_const_exprs` feature.

rust/kernel/transmute.rs

@@ -49,7 +49,6 @@ pub unsafe trait FromBytes {
         let slice_ptr = bytes.as_ptr().cast::<Self>();
         let size = size_of::<Self>();
 
-        #[allow(clippy::incompatible_msrv)]
         if bytes.len() == size && slice_ptr.is_aligned() {
             // SAFETY: Size and alignment were just checked.
             unsafe { Some(&*slice_ptr) }
@@ -92,7 +91,6 @@ pub unsafe trait FromBytes {
         let slice_ptr = bytes.as_mut_ptr().cast::<Self>();
         let size = size_of::<Self>();
 
-        #[allow(clippy::incompatible_msrv)]
         if bytes.len() == size && slice_ptr.is_aligned() {
             // SAFETY: Size and alignment were just checked.
             unsafe { Some(&mut *slice_ptr) }