media: cx23885: Add support for AVerMedia CE310B

The AVerMedia CE310B is a simple composite + S-Video + stereo audio
capture card, and uses only the CX23888 to perform all of these
functions.

I've tested both video inputs and the audio interface and confirmed that
they're all working. However, there are some issues:

* Sometimes when I switch inputs the video signal turns black and can't
  be recovered until the system is rebooted. I haven't been able to
  determine the cause of this behavior, nor have I found a solution to
  fix it or any workarounds other than rebooting.
* The card sometimes seems to have trouble syncing to the video signal,
  and some of the VBI data appears as noise at the top of the frame, but
  I assume that to be a result of my very noisy RF environment and the
  card's unshielded input traces rather than a configuration issue.

Signed-off-by: Forest Crossman <cyrozap@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>