In some controls the property can be listed twice so merge the flags

In the remote desktop client control there were separate entries for the
getter and setter of the properties and the flags for the getter would
override the other. Therefore the flags should be combined as the relevant
function would be used anyway for the purpose.

Change-Id: I212b23cf69c96be71dcd8a7493e8a57cb69ff5fe
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>