When added in multiple previous commits, it was used only with -device
qxl(-vga), but for some QEMUs (< 1.6) we need to add this
functionality when using -vga qxl as well.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1283207
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
