ANDROID: rust: security: mark Rust wrappers of security_binder_* inline

This prevents Rust from generating Rust symbols that are just trivial
wrappers around the underlying C symbols.

	$ nm vmlinux | grep ' _R.*security..binder' | rustfilt
	ffffffc0807829b0 T kernel::security::binder_transaction
	ffffffc080782ad0 T kernel::security::binder_transfer_file
	ffffffc080782920 T kernel::security::binder_set_context_mgr
	ffffffc080782a40 T kernel::security::binder_transfer_binder

This is a follow-up to aosp/3477716.

Bug: 403200195
Change-Id: I08e127243f7da354d09adb937b3f1d6ebeee751c
Signed-off-by: Alice Ryhl <aliceryhl@google.com>