rust: init: remove macros.rs

Since all initialization macros have been rewritten using `syn` and
`quote`, the `macros` module does no longer contain any code.
The only thing that is left is documentation that explains the expansion
of the initialization macros. This can now be directly observed in the
source code for the macros (found under `rust/macros`). Since the proc
macro code is much more readable than the declarative macro style.
Thus remove the expanded code.

Signed-off-by: Benno Lossin <[email protected]>

rust/kernel/init.rs

@@ -228,8 +228,6 @@ use core::{
 
 #[doc(hidden)]
 pub mod __internal;
-#[doc(hidden)]
-pub mod macros;
 
 /// Initialize and pin a type directly on the stack.
 ///