[media] r820t: add DVBC profile in sysfreq_sel

This will make the Astrometa DVB-T/T2/C usb stick be able to pick up
muxes around 290-314 MHz.

Signed-off-by: Benjamin Larsson <benjamin@southpole.se>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>