media: ddbridge: use common DVB I2C client handling helpers

Instead of keeping duplicated I2C client handling construct, make use of
the newly introduced dvb_module_*() helpers. This not only keeps things
way cleaner and removes the need for duplicated I2C client attach code,
but even allows to get rid of some variables that won't help in making
things look cleaner anymore.

The check on a valid ptr on port->en isn't really needed since the cxd2099
driver will set it at a time where it is going to return successfully
from probing.

Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>