[media] cx25840: Enable support for non-tuner LR1/LR2 audio inputs

The change effects cx23885 boards only and preserves support for existing
boards. Essentially, if we're using baseband audio into the cx23885 AV
core then we have to patch registers. The cx23885 driver will call
with either CX25840_AUDIO8 to signify tuner audio or AUDIO7 to
signify baseband audio. If/When we become more comfortable with this change
across a series of products then we may decide to relax the cx23885 only
restriction.

[liplianin@netup.ru: fix missing state declaration]

Signed-off-by: Steven Toth <stoth@kernellabs.com>
Signed-off-by: Igor M. Liplianin <liplianin@netup.ru>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>