[media] rtl28xxu: use rtl2832 demod callbacks accessing its resources

Switch demod resource use from exported symbols to callbacks its
provides.

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

diff --cc drivers/media/usb/dvb-usb-v2/rtl28xxu.c
Simple merge

diff --cc drivers/media/usb/dvb-usb-v2/rtl28xxu.h
Simple merge