io_uring: kill unused notif declarations

There are two leftover structures from the notification registration
mechanism that has never been released, kill them.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f05f65aebaf8b1b5bf28519a8fdb350e3e7c9ad0.1679924536.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

include/uapi/linux/io_uring.h

@@ -571,19 +571,6 @@ struct io_uring_rsrc_update2 {
 	__u32 resv2;
 };
 
-struct io_uring_notification_slot {
-	__u64 tag;
-	__u64 resv[3];
-};
-
-struct io_uring_notification_register {
-	__u32 nr_slots;
-	__u32 resv;
-	__u64 resv2;
-	__u64 data;
-	__u64 resv3;
-};
-
 /* Skip updating fd indexes set to this value in the fd table */
 #define IORING_REGISTER_FILES_SKIP	(-2)