V4L/DVB (12101): em28xx: add support for EVGA inDtube

Add support for the EVGA inDtube.  Both ATSC and analog side validated as
fully functional.

Thanks to Jake Crimmins from EVGA for providing the correct GPIO info.
Thanks to Alan Hagge for doing all the device testing.
Thanks to Greg Williamson for providing hardware for testing.

Cc: Jake Crimmins <jcrimmins@evga.com>
Cc: Alan Hagge <ahagge@gmail.com>
Cc: Greg Williamson <cheeseboy16@gmail.com>
Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>