modesetting: fix shadow resizing.
modesetting: fix shadow resizing.

if we hotplugged and output, the shadow got disabled by accident.

Signed-off-by: Dave Airlie <f2295d84e358395675bc8031be58672073ae065e@redhat.com>

wzyy2/xf86-video-modesetting,patjak/xf86-video-gma500,wzyy2/xf86-video-modesetting,patjak/xf86-video-gma500