Remove type id/name conversion for QVariant::UserType

Remove type id/name conversion for QVariant::UserType

QVariant::UserType does not correspond to an actual type named
"UserType". This logic didn't make sense.

Change-Id: I369911e514f7902fc863cb05174011d6fc15c447
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@nokia.com>
Reviewed-by: Jonas Gastal <jgastal@profusion.mobi>
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>