V4L/DVB (12475): Add support for Humax/Coex DVB-T USB Stick 2.0 High Speed

This patch adds support for Humax/Coex DVB-T USB Stick 2.0 High Speed
which is a very popular tuner sold in Vietnam.
Tested with at least 3 tuners.

Cc: Patrick Boettcher <pboettcher@kernellabs.com>
Signed-off-by: Pham Thanh Nam <phamthanhnam.ptn@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>