s390x: uv-guest: Test invalid commands

Lets check if the UV calls that should not be available in a
protected guest 2 are actually not available. Also lets check if they
are falsely indicated to be available.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: Thomas Huth <thuth@redhat.com>