[media] af9033: return regmap for integrated IT913x tuner driver

IT9130 series contains integrated tuner driver, which uses that
demodulator address space. Return regmap in order to allow it913x
driver communication.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>