V4L/DVB (3934): Support new dvb-ttusb-budget boards with stv0297

Added config switch to stv0297 to control i2c STOP during write behaviour.
Update frontend init in dvb-ttusb-budget.
Enable i2c STOP on other users of stv0297.

Signed-off-by: Thomas Kaiser <linux-dvb AT kaiser-linux.li>
Signed-off-by: Andrew de Quincey <adq_dvb@lidskialf.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>