io_uring: add type to op enum

It is useful to have a type enum for opcodes, to allow the compiler to
assert that every value is used in a switch statement.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220426082907.3600028-2-dylany@fb.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

include/uapi/linux/io_uring.h

@@ -105,7 +105,7 @@ enum {
 #define IORING_SETUP_R_DISABLED	(1U << 6)	/* start with ring disabled */
 #define IORING_SETUP_SUBMIT_ALL	(1U << 7)	/* continue submit on error */
 
-enum {
+enum io_uring_op {
 	IORING_OP_NOP,
 	IORING_OP_READV,
 	IORING_OP_WRITEV,