[media] vivid: add 1080p capture at 2 fps and 5 fps to webcam emulation

Use the VIVID_WEBCAM_SIZES constant where appropriate and add a
1920x1080 pixel frame size setting with frame rates of 2 fps and
5 fps.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>