drm/tilcdc: Restore old dpms state in pm_resume()

Restore old dpms state in pm_resume(). The dpms is turned off in
pm_suspend() and it should be restored to its original state in
pm_resume(). Without this patch the display is left blanked after a
suspend/resume cycle.

Fixes commit 614b3cfeb8d2 ("drm/tilcdc: disable the lcd controller/dma
engine when suspend invoked")

Signed-off-by: Jyri Sarha <jsarha@ti.com>
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.h b/drivers/gpu/drm/tilcdc/tilcdc_drv.h
index c1de18b..3b52ce8 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.h
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.h
@@ -67,6 +67,7 @@
 
 	/* register contents saved across suspend/resume: */
 	u32 *saved_register;
+	int saved_dpms_state;
 	bool ctx_valid;
 
 #ifdef CONFIG_CPU_FREQ
@@ -172,5 +173,6 @@
 int tilcdc_crtc_mode_valid(struct drm_crtc *crtc, struct drm_display_mode *mode);
 int tilcdc_crtc_max_width(struct drm_crtc *crtc);
 void tilcdc_crtc_dpms(struct drm_crtc *crtc, int mode);
+int tilcdc_crtc_current_dpms_state(struct drm_crtc *crtc);
 
 #endif /* __TILCDC_DRV_H__ */