io_uring: improve io_run_task_work()

Since SQPOLL now uses TWA_SIGNAL_NO_IPI, there won't be task work items
without TIF_NOTIFY_SIGNAL. Simplify io_run_task_work() by removing
task->task_works check. Even though looks it doesn't cause extra cache
bouncing, it's still nice to not touch it an extra time when it might be
not cached.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/75d4f34b0c671075892821a409e28da6cb1d64fe.1655802465.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/io_uring.h

@@ -203,7 +203,7 @@ static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)
 
 static inline bool io_run_task_work(void)
 {
-	if (test_thread_flag(TIF_NOTIFY_SIGNAL) || task_work_pending(current)) {
+	if (test_thread_flag(TIF_NOTIFY_SIGNAL)) {
 		__set_current_state(TASK_RUNNING);
 		clear_notify_signal();
 		if (task_work_pending(current))