Validate the domain configuration to ensure that if there are more than
one vgpu assigned to a domain, only one of them has 'ramfb' enabled.
This was never a supported configuration. QEMU failed confusingly when
attempting to start a domain with this configuration. This change
attempts to provide better information about the error.
https://bugzilla.redhat.com/show_bug.cgi?id=2079760
Signed-off-by: Jonathon Jongsma <jjongsma@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
