drm/qxl: recreate the primary surface when the bo is not primary

When disabling/enabling a crtc the primary area must be updated
independently of which crtc has been disabled/enabled.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1264735



Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>