media: dvb: earth-pt1: decompose pt1 driver into sub drivers

earth-pt1 was a monolithic module and included demod/tuner drivers.
This patch removes those FE parts and  attach demod/tuner i2c drivers.

Signed-off-by: Akihiro Tsukada <tskd08@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>