gma500: Fix backlight crash

Initial changes to get backlight behaviour we want and to fix backlight crashes
on suspend/resume paths.

[Note: on some boxes this will now produce a warning about the backlight, this
 isn't a regression it's an unfixed but non harmful case I still need to nail]

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/gma500/power.c b/drivers/gpu/drm/gma500/power.c
index 972bea7..9402569 100644
--- a/drivers/gpu/drm/gma500/power.c
+++ b/drivers/gpu/drm/gma500/power.c
@@ -302,7 +302,7 @@
 
 int psb_runtime_resume(struct device *dev)
 {
-	return 0;
+	return gma_power_resume(dev);;
 }
 
 int psb_runtime_idle(struct device *dev)