drm/gma500: Add hooks for hibernation

Currently we do whatever is done during suspend/resume but we might need some
more work for hibernation so keep them in separate functions.

Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>

drivers/gpu/drm/gma500/power.h

@@ -41,6 +41,9 @@ void gma_power_uninit(struct drm_device *dev);
  */
 int gma_power_suspend(struct device *dev);
 int gma_power_resume(struct device *dev);
+int gma_power_thaw(struct device *dev);
+int gma_power_freeze(struct device *dev);
+int gma_power_restore(struct device *_dev);
 
 /*
  * These are the functions the driver should use to wrap all hw access