Btrfs: fix invalid reference in replace_path

Dan Carpenter's static checker has found this error, it's introduced by
commit 64c043de466d
("Btrfs: fix up read_tree_block to return proper error")

It's really supposed to 'break' the loop on error like others.

Cc: Dan Carpenter <dan.carpenter@oracle.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/relocation.c

@@ -1850,6 +1850,7 @@ again:
 			eb = read_tree_block(dest, old_bytenr, old_ptr_gen);
 			if (IS_ERR(eb)) {
 				ret = PTR_ERR(eb);
+				break;
 			} else if (!extent_buffer_uptodate(eb)) {
 				ret = -EIO;
 				free_extent_buffer(eb);