io_uring: Remove unused function req_ref_put

Fix the following clang warnings:

fs/io_uring.c:1195:20: warning: unused function 'req_ref_put'
[-Wunused-function].

Fixes: aa43477b ("io_uring: poll rework")
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220113162005.3011-1-jiapeng.chong@linux.alibaba.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -1192,12 +1192,6 @@ static inline bool req_ref_put_and_test(struct io_kiocb *req)
 	return atomic_dec_and_test(&req->refs);
 }
 
-static inline void req_ref_put(struct io_kiocb *req)
-{
-	WARN_ON_ONCE(!(req->flags & REQ_F_REFCOUNT));
-	WARN_ON_ONCE(req_ref_put_and_test(req));
-}
-
 static inline void req_ref_get(struct io_kiocb *req)
 {
 	WARN_ON_ONCE(!(req->flags & REQ_F_REFCOUNT));