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/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 8871662..df9e0b3 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -56,7 +56,7 @@
 	return bl->props.brightness;
 }
 
-static struct backlight_ops pwm_backlight_ops = {
+static const struct backlight_ops pwm_backlight_ops = {
 	.update_status	= pwm_backlight_update_status,
 	.get_brightness	= pwm_backlight_get_brightness,
 };