media: ddbridge: get rid of fall though gcc 7.1 warnings

media: ddbridge: get rid of fall though gcc 7.1 warnings

drivers/media/pci/ddbridge/ddbridge-core.c: In function 'ddb_port_attach':
drivers/media/pci/ddbridge/ddbridge-core.c:2261:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (ret < 0)
      ^
drivers/media/pci/ddbridge/ddbridge-core.c:2263:2: note: here
  case DDB_PORT_LOOP:
  ^~~~
drivers/media/pci/ddbridge/ddbridge-core.c: In function 'dvb_input_attach':
drivers/media/pci/ddbridge/ddbridge-core.c:1492:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (input->port->dev->link[input->port->lnr].info->ts_quirks &
      ^
drivers/media/pci/ddbridge/ddbridge-core.c:1497:2: note: here
  case DDB_TUNER_DVBCT2_SONY_P:
  ^~~~
drivers/media/pci/ddbridge/ddbridge-core.c:1516:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
   osc24 = 1;
   ~~~~~~^~~
drivers/media/pci/ddbridge/ddbridge-core.c:1517:2: note: here
  case DDB_TUNER_DVBCT2_SONY:
  ^~~~

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>