fbdev: sh_mobile_lcdc: Store the backlight brightness internally

There's no need to query the hardware for the currenty brightness value
through a platform data callback when we can cache the value internally
in the LCDC driver.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
diff --git a/drivers/video/sh_mobile_lcdcfb.h b/drivers/video/sh_mobile_lcdcfb.h
index 0f92f65..f839ade 100644
--- a/drivers/video/sh_mobile_lcdcfb.h
+++ b/drivers/video/sh_mobile_lcdcfb.h
@@ -94,6 +94,7 @@
 
 	/* Backlight */
 	struct backlight_device *bl;
+	unsigned int bl_brightness;
 
 	/* FB */
 	struct fb_info *info;