[media] v4l2: add const to argument of write-only s_register ioctl

This ioctl is defined as IOW, so pass the argument as const.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/dvb-frontends/au8522_decoder.c b/drivers/media/dvb-frontends/au8522_decoder.c
index 5243ba6..526902b 100644
--- a/drivers/media/dvb-frontends/au8522_decoder.c
+++ b/drivers/media/dvb-frontends/au8522_decoder.c
@@ -583,7 +583,7 @@
 }
 
 static int au8522_s_register(struct v4l2_subdev *sd,
-			     struct v4l2_dbg_register *reg)
+			     const struct v4l2_dbg_register *reg)
 {
 	struct i2c_client *client = v4l2_get_subdevdata(sd);
 	struct au8522_state *state = to_state(sd);