media: ngene: use common DVB I2C client handling helpers

Like in ddbridge, get rid of all duplicated I2C client handling constructs
and rather make use of the newly added dvb_module_*() helpers. Makes
things more clean and removes the (cosmetic) need for some variables.

The check on a valid ptr on ci->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>