[media] si2157: extend frequency range for DVB-C

DVB-C uses lower frequencies than DVB-T. Extend frequency range down to
110 MHz in order to support DVB-C. 110 - 862 MHz range is defined by
NorDig Unified 2.2 specification.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>