V4L/DVB (5778): Dvb-usb: kill unused tuner/i2c functions

These two functions are no longer being used:
	dvb_usb_tuner_init_i2c
	dvb_usb_tuner_set_params_i2c

This functionality has been taken over by dvb-pll

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