[PATCH] rust: cpufreq: clean new `clippy::map_or_identity` lint for Rust 1.98.0

[Miguel Ojeda <ojeda@kernel.org>]

Starting with Rust 1.98.0 (expected 2026-08-20), Clippy is likely
introducing a new lint `clippy::map_or_identity` [1][2], which currently
triggers in a single case:

    warning: expression can be simplified using `Result::unwrap_or()`
        --> rust/kernel/cpufreq.rs:1326:60
         |
    1326 |         PolicyCpu::from_cpu(cpu_id).map_or(0, |mut policy| T::get(&mut policy).map_or(0, |f| f))
         |                                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
         |
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#map_or_identity
         = note: `-W clippy::map-or-identity` implied by `-W clippy::all`
         = help: to override `-W clippy::all` add `#[allow(clippy::map_or_identity)]`
    help: consider using `unwrap_or`
         |
    1326 -         PolicyCpu::from_cpu(cpu_id).map_or(0, |mut policy| T::get(&mut policy).map_or(0, |f| f))
    1326 +         PolicyCpu::from_cpu(cpu_id).map_or(0, |mut policy| T::get(&mut policy).unwrap_or(0))
         |

The suggestion is valid, thus clean it up.

Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: https://github.com/rust-lang/rust-clippy/issues/15801 [1]
Link: https://github.com/rust-lang/rust-clippy/pull/16052 [2]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/kernel/cpufreq.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index d8d26870bea2..a20bd5006f38 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -1323,7 +1323,7 @@ impl<T: Driver> Registration<T> {
         // SAFETY: The C API guarantees that `cpu` refers to a valid CPU number.
         let cpu_id = unsafe { CpuId::from_u32_unchecked(cpu) };
 
-        PolicyCpu::from_cpu(cpu_id).map_or(0, |mut policy| T::get(&mut policy).map_or(0, |f| f))
+        PolicyCpu::from_cpu(cpu_id).map_or(0, |mut policy| T::get(&mut policy).unwrap_or(0))
     }
 
     /// Driver's `update_limit` callback.

base-commit: 420dd187e1572bb7e232781bc4377a80c8eb64fb
-- 
2.54.0