[media] saa7134: fix warm Medion 7134 EEPROM read

When saa7134 module driving a Medion 7134 card is reloaded reads of this
card EEPROM (required for automatic detection of tuner model) will be
corrupted due to I2C gate in DVB-T demod being left closed.
This sometimes also happens on first saa7134 module load after a warm
reboot.

Fix this by opening this I2C gate before doing EEPROM read during i2c
initialization.

Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>