ioctx_alloc(): remove pointless check

Way, way back kiocb used to be picked from arrays, so ioctx_alloc()
checked for multiplication overflow when calculating the size of
such array.  By the time fs/aio.c went into the tree (in 2002) they
were already allocated one-by-one by kmem_cache_alloc(), so that
check had already become pointless.  Let's bury it...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/aio.c

@@ -688,8 +688,7 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
 	nr_events *= 2;
 
 	/* Prevent overflows */
-	if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
-	    (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
+	if (nr_events > (0x10000000U / sizeof(struct io_event))) {
 		pr_debug("ENOMEM: nr_events too high\n");
 		return ERR_PTR(-EINVAL);
 	}