V4L/DVB: s2255drv: support for frame skipping

adds hardware frame skipping using VIDIOC_S_PARM ioctl.
adds support for VIDIOC_ENUM_FRAMEINTERVALS.

Signed-off-by: Dean Anderson <dean@sensoray.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>