media: cxd2099: move driver out of staging into dvb-frontends

According to the TODO file, this driver only landed in staging because of
the way device nodes and data transfers are handled. Besides that this way
(use of secX devices) has become sort of standard to date (ie. VDR
supports this literally since ages via the ddci plugin, TVHeadend received
this functionality lately, and minisatip being currently worked on
regarding this), most importantly this I2C client only driver isn't even
responsible for setting up device nodes, not for handling data
transfer and so on, but only serves as interface for the dvb_ca_en50221
subsystem, just like every other DVB card out in the wild, with hard-wired
or such flexible CA interfaces. And, it would even work with cards having
the cxd2099 controller hard-wired.

Also, this driver received quite some love and even is a proper I2C client
driver by now. So, as this driver acts as a EN50221 frontend device, move
it to dvb-frontends. There is no need to keep it buried in staging.

This commit also updates all affected Kconfig and Makefile's, and adds
MEDIA_AUTOSELECT depends to ddbridge and ngene.

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