ivtv: fix VIDIOC_S_FBUF support: new OSD values where never actually set.

The values set with VIDIOC_S_FBUF were not actually used until the next
VIDIOC_S_FMT. Fixed.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>