V4L/DVB (9578): v4l core: add support for enumerating frame sizes and intervals

video_ioctl2 lacks implementation of those two ioctls:
	- VIDIOC_ENUM_FRAMESIZES and VIDIOC_ENUM_FRAMEINTERVALS

Adds implementation for those.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>