io_uring: remove dead struct io_submit_state member

When the intermediate CQE aux cache got removed, any usage of the this
member went away. As it isn't used anymore, kill it.

Fixes: 902ce82c ("io_uring: get rid of intermediate aux cqe caches")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/io_uring_types.h

@@ -207,7 +207,6 @@ struct io_submit_state {
 	bool			need_plug;
 	bool			cq_flush;
 	unsigned short		submit_nr;
-	unsigned int		cqes_count;
 	struct blk_plug		plug;
 };