[media] rtl2832: convert driver to I2C binding

Convert that driver to I2C driver model.
Legacy DVB binding is left also for later removal...

Tested-by: Benjamin Larsson <benjamin@southpole.se>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>