[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/pci/saa7146/mxb.c b/drivers/media/pci/saa7146/mxb.c
index 27dc49b..9dd044b 100644
--- a/drivers/media/pci/saa7146/mxb.c
+++ b/drivers/media/pci/saa7146/mxb.c
@@ -560,7 +560,7 @@
 	return call_all(dev, tuner, g_tuner, t);
 }
 
-static int vidioc_s_tuner(struct file *file, void *fh, struct v4l2_tuner *t)
+static int vidioc_s_tuner(struct file *file, void *fh, const struct v4l2_tuner *t)
 {
 	struct saa7146_dev *dev = ((struct saa7146_fh *)fh)->dev;
 	struct mxb *mxb = (struct mxb *)dev->ext_priv;