[media] v4l2: make vidioc_s_audout const

Write-only ioctls should have a const argument in the ioctl op.
Do this conversion for vidioc_s_audout.
Adding const for write-only ioctls was decided during the 2012 Media Workshop.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/pci/ivtv/ivtv-ioctl.c

@@ -813,11 +813,13 @@ static int ivtv_g_audout(struct file *file, void *fh, struct v4l2_audioout *vin)
 	return ivtv_get_audio_output(itv, vin->index, vin);
 }
 
-static int ivtv_s_audout(struct file *file, void *fh, struct v4l2_audioout *vout)
+static int ivtv_s_audout(struct file *file, void *fh, const struct v4l2_audioout *vout)
 {
 	struct ivtv *itv = fh2id(fh)->itv;
 
-	return ivtv_get_audio_output(itv, vout->index, vout);
+	if (itv->card->video_outputs == NULL || vout->index != 0)
+		return -EINVAL;
+	return 0;
 }
 
 static int ivtv_enum_input(struct file *file, void *fh, struct v4l2_input *vin)

drivers/media/radio/radio-si4713.c

@@ -83,7 +83,7 @@ static int radio_si4713_g_audout(struct file *file, void *priv,
 }
 
 static int radio_si4713_s_audout(struct file *file, void *priv,
-					struct v4l2_audioout *vao)
+					const struct v4l2_audioout *vao)
 {
 	return vao->index ? -EINVAL : 0;
 }

include/media/v4l2-ioctl.h

@@ -175,7 +175,7 @@ struct v4l2_ioctl_ops {
 	int (*vidioc_g_audout)         (struct file *file, void *fh,
 					struct v4l2_audioout *a);
 	int (*vidioc_s_audout)         (struct file *file, void *fh,
-					struct v4l2_audioout *a);
+					const struct v4l2_audioout *a);
 	int (*vidioc_g_modulator)      (struct file *file, void *fh,
 					struct v4l2_modulator *a);
 	int (*vidioc_s_modulator)      (struct file *file, void *fh,