[media] si2157: add support for SYS_DVBC_ANNEX_B

Set the property for delivery system also in case of SYS_DVBC_ANNEX_B.
This behaviour is observed in the sniffs taken with Hauppauge HVR-955Q
Windows driver.

Signed-off-by: Olli Salonen <olli.salonen@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>