io_uring: kill NULL checks for submit state

After recent changes, io_submit_sqes() always passes valid submit state,
so kill leftovers checking it for NULL.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -1376,11 +1376,7 @@ static struct io_kiocb *io_alloc_req(struct io_ring_ctx *ctx,
 	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
 	struct io_kiocb *req;
 
-	if (!state) {
-		req = kmem_cache_alloc(req_cachep, gfp);
-		if (unlikely(!req))
-			goto fallback;
-	} else if (!state->free_reqs) {
+	if (!state->free_reqs) {
 		size_t sz;
 		int ret;