Btrfs: fix wrong check for btrfs_force_chunk_alloc()

btrfs_force_chunk_alloc() return 1 for allocation chunk successfully.
This problem exists since commit c87f08ca.

With this patch, we might fix some enospc problems for balances.
Signed-off-by: Wang Shilong <wangshilong1991@gmail.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Tested-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>

fs/btrfs/relocation.c

@@ -4049,7 +4049,7 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 	if (trans && progress && err == -ENOSPC) {
 		ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
 					      rc->block_group->flags);
-		if (ret == 0) {
+		if (ret == 1) {
 			err = 0;
 			progress = 0;
 			goto restart;