[media] v4l2: make vidioc_s_fbuf const

Write-only ioctls should have a const argument in the ioctl op.
Do this conversion for vidioc_s_fbuf.
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>
diff --git a/drivers/media/pci/ivtv/ivtv-ioctl.c b/drivers/media/pci/ivtv/ivtv-ioctl.c
index 32a5910..d3b32c2 100644
--- a/drivers/media/pci/ivtv/ivtv-ioctl.c
+++ b/drivers/media/pci/ivtv/ivtv-ioctl.c
@@ -1427,7 +1427,7 @@
 	return 0;
 }
 
-static int ivtv_s_fbuf(struct file *file, void *fh, struct v4l2_framebuffer *fb)
+static int ivtv_s_fbuf(struct file *file, void *fh, const struct v4l2_framebuffer *fb)
 {
 	struct ivtv_open_id *id = fh2id(fh);
 	struct ivtv *itv = id->itv;
@@ -1444,7 +1444,7 @@
 	itv->osd_chroma_key_state = (fb->flags & V4L2_FBUF_FLAG_CHROMAKEY) != 0;
 	ivtv_set_osd_alpha(itv);
 	yi->track_osd = (fb->flags & V4L2_FBUF_FLAG_OVERLAY) != 0;
-	return ivtv_g_fbuf(file, fh, fb);
+	return 0;
 }
 
 static int ivtv_overlay(struct file *file, void *fh, unsigned int on)