btrfs: zoned: fix chunk map leak when loading block group zone info

At btrfs_load_block_group_zone_info() we never drop a reference on the
chunk map we have looked up, therefore leaking a reference on it. So
add the missing btrfs_free_chunk_map() at the end of the function.

Fixes: 7dc66abb ("btrfs: use a dedicated data structure for chunk maps")
Reported-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/zoned.c

@@ -1687,6 +1687,7 @@ int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache, bool new)
 	}
 	bitmap_free(active);
 	kfree(zone_info);
+	btrfs_free_chunk_map(map);
 
 	return ret;
 }