[media] cx18: Add support for Hauppauge HVR-1600 models with s5h1411

The newest variants of the HVR-1600 have an s5h1411/tda18271 for the digital
frontend.  Add support for these boards.

Thanks to Hauppauge Computer Works for providing sample hardware.

[awalls@md.metrocast.net: Changed an additional log message to clarify for
the end user that the driver is defaulting to an original HVR-1600 for
unknown model numbers.]

Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>