backlight: Revert some const qualifiers

9905a43 went a little to far with const
qualifiers as there are legitiment cases where the function pointers
can change (machine specific setup code for example).

Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

include/linux/backlight.h

@@ -36,18 +36,18 @@ struct backlight_device;
 struct fb_info;
 
 struct backlight_ops {
-	const unsigned int options;
+	unsigned int options;
 
 #define BL_CORE_SUSPENDRESUME	(1 << 0)
 
 	/* Notify the backlight driver some property has changed */
-	int (* const update_status)(struct backlight_device *);
+	int (*update_status)(struct backlight_device *);
 	/* Return the current backlight brightness (accounting for power,
 	   fb_blank etc.) */
-	int (* const get_brightness)(struct backlight_device *);
+	int (*get_brightness)(struct backlight_device *);
 	/* Check if given framebuffer device is the one bound to this backlight;
 	   return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
-	int (* const check_fb)(struct fb_info *);
+	int (*check_fb)(struct fb_info *);
 };
 
 /* This structure defines all the properties of a backlight */