io_uring: kill unused IO_IOPOLL_BATCH

IO_IOPOLL_BATCH is not used, delete it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b2bdf19dbee2c9fc8865bbab9412135a14e24a64.1628471125.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -295,7 +295,6 @@ struct io_sq_data {
 	struct completion	exited;
 };
 
-#define IO_IOPOLL_BATCH			8
 #define IO_COMPL_BATCH			32
 #define IO_REQ_CACHE_SIZE		32
 #define IO_REQ_ALLOC_BATCH		8