drm: fix fb refcount issue with atomic modesetting

drm: fix fb refcount issue with atomic modesetting

After commit 85e9be3c4c6df02f21c5229c8084946bc8d744cc ("drm/modes: stop
handling framebuffer special") extra fb refs are left around when doing
atomic modesetting.

The problem is that the new drm_property_change_valid_get() does not
return anything in the '**ref' parameter, which causes
drm_property_change_valid_put() to do nothing.

For some reason this doesn't cause problems with legacy API.

Also, previously the code only set the 'ref' variable for fbs, with this
patch the 'ref' is set for all objects.

Fixes: 85e9be3c4c6d ("drm/modes: stop handling framebuffer special")
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>