[media] add frame size/frame rate query functions

Add missing functions to query the single fixed frame size (960x540) and
supported frame rates. Technically, the SUR40 supports any arbitrary frame
rate up to 60 FPS, as it is polled and not interrupt-driven. For now, we
just report 30 and 60 FPS, which is sufficient to make most V4L2 tools work.

Signed-off-by: Martin Kaltenbrunner <modin@yuri.at>
Signed-off-by: Florian Echtler <floe@butterbrot.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>