[media] mt9v032: use regmap

This switches all register accesses to use regmap. It allows to
use the regmap cache, tracing, and debug register dump facilities,
and removes the need to open code read-modify-writes.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>