btrfs: go to matching label when cleaning em in btrfs_submit_direct

When btrfs_get_chunk_map fails to allocate a new em the cleanup does not
need to be done so the goto target is out_err, which is consistent with
current coding style.

Signed-off-by: Peng Hao <flyingpeng@tencent.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>