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/video/aty/aty128fb.c b/drivers/video/aty/aty128fb.c
index 34a0851..dd9de2e 100644
--- a/drivers/video/aty/aty128fb.c
+++ b/drivers/video/aty/aty128fb.c
@@ -1786,7 +1786,7 @@
 	return bd->props.brightness;
 }
 
-static struct backlight_ops aty128_bl_data = {
+static const struct backlight_ops aty128_bl_data = {
 	.get_brightness	= aty128_bl_get_brightness,
 	.update_status	= aty128_bl_update_status,
 };