backlight: Constify struct backlight_ops

Signed-off-by: Emese Revfy <re.emese@gmail.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
diff --git a/drivers/video/backlight/mbp_nvidia_bl.c b/drivers/video/backlight/mbp_nvidia_bl.c
index 9edb8d7..5812468 100644
--- a/drivers/video/backlight/mbp_nvidia_bl.c
+++ b/drivers/video/backlight/mbp_nvidia_bl.c
@@ -33,7 +33,7 @@
 	unsigned long iostart;
 	unsigned long iolen;
 	/* Backlight operations structure. */
-	struct backlight_ops backlight_ops;
+	const struct backlight_ops backlight_ops;
 };
 
 /* Module parameters. */