V4L/DVB (9232): cx23885: Move the MFE frontend allocation into the correct place

cx23885 frontend allocation code needs to exist in the higher function,
and it also needs to ensure videobug is also correctly initialised
on a per frontend basis. This code uses the previous num_frontends
patch to safely init each future MFE frontend on a single tsport as
as safely as possible - given that we don't have any of those boards.
Again, better to add all of this safety code now, while the MFE patch
set is fresh in everyone mind, than to try and add it 12-24 months from
now, when the subject is cold.

Signed-off-by: Steven Toth <stoth@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>