rust: optimize rust symbol generation for SeqFile

When build the kernel using the llvm-18.1.3-rust-1.85.0-x86_64
with ARCH=arm64, the following symbols are generated:

$nm vmlinux | grep ' _R'.*SeqFile | rustfilt
ffff8000805b78ac T <kernel::seq_file::SeqFile>::call_printf

This Rust symbol is trivial wrappers around the C functions seq_printf.
It doesn't make sense to go through a trivial wrapper for its functions,
so mark it inline.

Link: #1145
Suggested-by: Alice Ryhl <aliceryhl@google.com>
Co-developed-by: Grace Deng <Grace.Deng006@Gmail.com>
Signed-off-by: Grace Deng <Grace.Deng006@Gmail.com>
Signed-off-by: Kunwu Chan <kunwu.chan@hotmail.com>
Link: https://lore.kernel.org/r/20250317030418.2371265-1-kunwu.chan@linux.dev
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: KunWuChan

rust/kernel/seq_file.rs

@@ -30,6 +30,7 @@ impl SeqFile {
     }
 
     /// Used by the [`seq_print`] macro.
+    #[inline]
     pub fn call_printf(&self, args: core::fmt::Arguments<'_>) {
         // SAFETY: Passing a void pointer to `Arguments` is valid for `%pA`.
         unsafe {