V4L/DVB (8657): cxusb: add lgs8gl5 and support for Magic-Pro DMB-TH usb stick

Add support for Magic-Pro DMB-TH usb stick.  DMB-TH is the HDTV broadcast
standard used in Hong Kong and China.
[...]
I've also attached a second patch against the dvb-apps repository which
adds a DMB-TH scan file for Hong Kong.

Since the ProHDTV stick contains a DMB-TH decoder (lgs8gl5) onboard,
it outputs MPEG-TS to the PC.

Signed-off-by: Timothy Lee <timothy.lee@siriushk.com>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>