Add a 2x2 checker patterns and 1x1 and 2x2 red/blue checker patterns.

Useful for testing 4:2:2 and 4:2:0 formats.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>