[media] cx231xx: Add a driver for I2C-based IR

Although cx231xx has a very good IR support, already supported by
mceusb driver, some designs decided to add a separate I2C
microcontroller chip in order to handle IR.

Due to that, add a glue to ir-kbd-i2c is needed, in order to support
those devices.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>