btrfs_ioctl_send(): don't bother with access_ok()

we do copy_from_user() on that range anyway
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/btrfs/send.c

@@ -7065,13 +7065,6 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
 		goto out;
 	}
 
-	if (!access_ok(arg->clone_sources,
-			sizeof(*arg->clone_sources) *
-			arg->clone_sources_count)) {
-		ret = -EFAULT;
-		goto out;
-	}
-
 	if (arg->flags & ~BTRFS_SEND_FLAG_MASK) {
 		ret = -EINVAL;
 		goto out;