rust/kernel/faux: mark Registration methods inline

When building the kernel on Arch Linux using on x86_64 with tools:
$ rustc --version
rustc 1.84.0 (9fc6b4312 2025-01-07)
$ clang --version
clang version 19.1.7
Target: x86_64-pc-linux-gnu

The following symbols are generated:
$ nm vmlinux | rg ' _R' | rustfilt | rg faux
ffffffff81959ae0 T <kernel::faux::Registration>::new
ffffffff81959b40 T <kernel::faux::Registration as core::ops::drop::Drop>::drop

However, these Rust symbols are wrappers around bindings in the C faux
code. Inlining these functions removes the middle-man wrapper function
After applying this patch, the above function signatures disappear.

Link: https://github.com/Rust-for-Linux/linux/issues/1145
Signed-off-by: Ethan Carter Edwards <ethan@ethancedwards.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/jesg4yu7m6fvzmgg5tlsktrrjm36l4qsranto5mdmnucx4pvf3@nhvt4juw5es3
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

rust/kernel/faux.rs

@@ -23,6 +23,7 @@ pub struct Registration(NonNull<bindings::faux_device>);
 
 impl Registration {
     /// Create and register a new faux device with the given name.
+    #[inline]
     pub fn new(name: &CStr, parent: Option<&device::Device>) -> Result<Self> {
         // SAFETY:
         // - `name` is copied by this function into its own storage
@@ -58,6 +59,7 @@ impl AsRef<device::Device> for Registration {
 }
 
 impl Drop for Registration {
+    #[inline]
     fn drop(&mut self) {
         // SAFETY: `self.0` is a valid registered faux_device via our type invariants.
         unsafe { bindings::faux_device_destroy(self.as_raw()) }