iBx000: add addition i2c-interface names

This patch adds the possibitity to use different I2C-ports to talk to
slave-devices than the standard ones.

Signed-off-by: Olivier Grenie <olivier.grenie@dibcom.fr>
Signed-off-by: Patrick Boettcher <patrick.boettcher@dibcom.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
}