V4L/DVB (7469): Preparation for supporting new devices, cleanup and saneness

V4L/DVB (7469): Preparation for supporting new devices, cleanup and saneness

To prepare the support for new device to the flexcop-family some preparation and cleanups was done + some saneness:

- created an i2c-adapter for each i2c-port available. Easier usage for devices with several device on different i2c-busses
- initialize i2c before doing the eeprom read
- changed the way to attach the different frontends, easier to read now
- enabled support for i2c-devices having no register address (1-byte access)

Signed-off-by: Patrick Boettcher <pb@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>