According the api schema of cinder, create_group_from_src
should only specify one of arguments from [group_snapshot_id, source_group_id].
Now cinderclient specified them both even if one of them is None.
This patch fix this issue to just pass one argument.
Change-Id: Idef51ab9a1452dd5eb3be4d4b6dca095a777d611
Closes-Bug: #1777555