rust: irq: always inline functions using build_assert with arguments

`build_assert` relies on the compiler to optimize out its error path.
Functions using it with its arguments must thus always be inlined,
otherwise the error path of `build_assert` might not be optimized out,
triggering a build error.

Cc: [e-mail]
Fixes: 746680ec6696 ("rust: irq: add flags module")
Reviewed-by: Daniel Almeida <[e-mail]>
Signed-off-by: Alexandre Courbot <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Danilo Krummrich <[e-mail]>

rust/kernel/irq/flags.rs

···
         self.0
     }
 
+    // Always inline to optimize out error path of `build_assert`.
+    #[inline(always)]
     const fn new(value: u32) -> Self {
         build_assert!(value as u64 <= c_ulong::MAX as u64);
         Self(value as c_ulong)