[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/saa7134/saa7134-video.c b/drivers/media/pci/saa7134/saa7134-video.c
index 6de10b1..bac4386 100644
--- a/drivers/media/pci/saa7134/saa7134-video.c
+++ b/drivers/media/pci/saa7134/saa7134-video.c
@@ -2158,7 +2158,7 @@
 }
 
 static int saa7134_s_fbuf(struct file *file, void *f,
-					struct v4l2_framebuffer *fb)
+					const struct v4l2_framebuffer *fb)
 {
 	struct saa7134_fh *fh = f;
 	struct saa7134_dev *dev = fh->dev;