video: sunxi: extract simplefb match code to a new file

As the DE2 simplefb setup code can also benefit from the simplefb match
code, extract it to a new source file.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>