V4L/DVB (8958): zr36067: Return proper bytes-per-line value

The zr36067 driver should return the actual bytes-per-line value when
queried with ioctl VIDIOC_G_FMT, instead of 0. Otherwise user-space
applications can get confused.

Likewise, with ioctl VIDIOC_S_FMT, we are supposed to fill the
bytes-per-line value. And we shouldn't fail if the caller sets the
initial value to something different from 0. This is perfectly valid
for applications to pre-fill this field with the value they expect.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>