demarshal: prefix variable name with parent names
demarshal: prefix variable name with parent names

Avoid naming clash if parent structures have the same name

https://bugzilla.redhat.com/show_bug.cgi?id=1021995

SPICE/spice-protocol,vdiot/spice-protocol,vdiot/spice-protocol,vdiot/spice-protocol,fgouget/spice-protocol,SPICE/spice-protocol,fgouget/spice-protocol,fgouget/spice-protocol,SPICE/spice-protocol