soc-camera: ov772x: Modify buswidth control

This patch removes "buswidth" struct member, and sets the default buswidth
to the natively supported 10 bit. You can select 8 bit buswidth by new flag.
This patch also modify ap325rxa/migor setup.c

Signed-off-by: Kuninori Morimoto <morimoto.kuninori@renesas.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>