Btrfs: remove warn on in free space cache writeout

This catches block groups that are too large to properly cache.  We deal with
this case fine, so the warning just confuses users.  Remove the warning.
Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>

fs/btrfs/free-space-cache.c

@@ -920,10 +920,8 @@ static int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 
 	/* Make sure we can fit our crcs into the first page */
 	if (io_ctl.check_crcs &&
-	    (io_ctl.num_pages * sizeof(u32)) >= PAGE_CACHE_SIZE) {
-		WARN_ON(1);
+	    (io_ctl.num_pages * sizeof(u32)) >= PAGE_CACHE_SIZE)
 		goto out_nospc;
-	}
 
 	io_ctl_set_generation(&io_ctl, trans->transid);