[media] rtl2832: remove internal mux I2C adapter

There was 2 muxed I2C adapters, one for demod tuner bus and one for
internal use. Idea of internal I2C adapter was to force I2C repeater
close when demod access its registers. Driver has also delayed work
queue based method to close I2C repeater.

After regmap conversion internal I2C adapter based repeater close
left unused - only work queue method was in use. We could not use
internal mux adapter method with regmap as it makes recursive regmap
call, which causes deadlock as regmap has own locking. Due to that
remove whole method totally.

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