[media] get_dvb_firmware: add logic to get sms1xx-hcw* firmware

The firmwares are there at the same place for a long time. However,
each time I need to remember where it is, I need to seek at the net.

The better is to just add a logic at the get_dvb_firmare script,
in order to obtain it from a reliable source.

Cc: Steven Toth <stoth@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>