[media] cx231xx: remember status of i2c port_3 switch

This is used later for is_tuner function that switches i2c behaviour for
some tuners.

[mchehab@osg.samsung.com: Fix CodingStyle on a multi-line comment]

Signed-off-by: Matthias Schwarzott <zzam@gentoo.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>