btrfs: Remove superfluous check form btrfs_remove_chunk

It's unnecessary to check map->stripes[i].dev for NULL given its value
is already set and dereferenced above the the check. No functional
changes.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -2848,15 +2848,13 @@ int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
 			mutex_unlock(&fs_info->chunk_mutex);
 		}
 
-		if (map->stripes[i].dev) {
-			ret = btrfs_update_device(trans, map->stripes[i].dev);
+		ret = btrfs_update_device(trans, device);
 		if (ret) {
 			mutex_unlock(&fs_devices->device_list_mutex);
 			btrfs_abort_transaction(trans, ret);
 			goto out;
 		}
 	}
-	}
 	mutex_unlock(&fs_devices->device_list_mutex);
 
 	ret = btrfs_free_chunk(trans, chunk_offset);