rust: block: remove trait bound from struct

Author: Andreas Hindborg

rust/kernel/block/mq/request.rs

@@ -57,7 +57,7 @@ use core::{
 /// [`struct request`]: srctree/include/linux/blk-mq.h
 ///
 #[repr(transparent)]
-pub struct Request<T: Operations>(Opaque<bindings::request>, PhantomData<T>);
+pub struct Request<T>(Opaque<bindings::request>, PhantomData<T>);
 
 impl<T: Operations> Request<T> {
     /// Create an [`ARef<Request>`] from a [`struct request`] pointer.