V4L/DVB (11951): cx18: Add DVB-T support for the Leadtek WinFast DVR3100 H

This adds support for DVB-T on the Leadtek DVR3100 H and should also get analog
TV capture from the tuner working properly as well.

DVB-T 6 MHz and 8 MHz have been tested and verified to work by Terry Wu of
Leadtek.  DVB-T 7 MHz has also been verified working with a change developed by
Terry to the tuner-xc2028.c driver.

Special thanks go to Terry Wu <terrywu2009@gmail.com> of Leadtek who provided
the needed information and testing to get digital TV working for the Leadtek
DVR3100 H.

Reported-by: Terry Wu <terrywu2009@gmail.com>
Tested-by: Terry Wu <terrywu2009@gmail.com>
Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>