Add DVB-T support for Yuan MPC-718 cards with an MT352 or ZL10353 demodulator.

There are apparently some units with a DiBcom demodulator which could be
supported by one of the dib7000 modules - but this is not implemented in the
cx18 driver (yet).

Due to lack of porgramming details for the MT352 and the mt352 module requiring
a "demod_init" function, a "firmware" must be obtained and loaded to get
DVB-T working for Yuan MPC-718 cards with an MT352.
Tested-by: Steve Firth <firth650@btinternet.com>
Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>