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

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

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Alexey Klimov <klimov.linux@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/radio/radio-cadet.c b/drivers/media/radio/radio-cadet.c
index 59be293..545c04c 100644
--- a/drivers/media/radio/radio-cadet.c
+++ b/drivers/media/radio/radio-cadet.c
@@ -390,7 +390,7 @@
 }
 
 static int vidioc_s_tuner(struct file *file, void *priv,
-				struct v4l2_tuner *v)
+				const struct v4l2_tuner *v)
 {
 	return v->index ? -EINVAL : 0;
 }