backlight: constify backlight_ops

backlight_device_register has been expecting a const "ops" argument, and using
it as such, since 9905a43b2d563e6f89e4c63c4278ada03f2ebb14. Let's make the
remaining backlight_ops instances const.

Inspired by hunks of the grsecurity patch, updated for newer kernels.

Signed-off-by: Lionel Debroux <lionel_debroux@yahoo.fr>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/macintosh/via-pmu-backlight.c b/drivers/macintosh/via-pmu-backlight.c
index 1cec02f..ade1e65 100644
--- a/drivers/macintosh/via-pmu-backlight.c
+++ b/drivers/macintosh/via-pmu-backlight.c
@@ -15,7 +15,7 @@
 
 #define MAX_PMU_LEVEL 0xFF
 
-static struct backlight_ops pmu_backlight_data;
+static const struct backlight_ops pmu_backlight_data;
 static DEFINE_SPINLOCK(pmu_backlight_lock);
 static int sleeping, uses_pmu_bl;
 static u8 bl_curve[FB_BACKLIGHT_LEVELS];
@@ -115,7 +115,7 @@
 	return bd->props.brightness;
 }
 
-static struct backlight_ops pmu_backlight_data = {
+static const struct backlight_ops pmu_backlight_data = {
 	.get_brightness	= pmu_backlight_get_brightness,
 	.update_status	= pmu_backlight_update_status,