[media] ts2020: register I2C driver from legacy media attach

Register driver using I2C bindings internally when legacy media
attach is used. That is done by registering driver using I2C binding
from legacy attach. That way we can get valid I2C client, which is
needed for proper dev_() logging and regmap for example even legacy
binding is used.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>