V4L/DVB (6224): VIDEO_CX23885 depends on DVB_CORE

Fix the following dependency issue:

ERROR: "dvb_dmx_init" [drivers/media/video/video-buf-dvb.ko] undefined!
ERROR: "dvb_unregister_adapter" [drivers/media/video/video-buf-dvb.ko] undefined!
ERROR: "dvb_register_frontend" [drivers/media/video/video-buf-dvb.ko] undefined!
ERROR: "dvb_unregister_frontend" [drivers/media/video/video-buf-dvb.ko] undefined!
ERROR: "dvb_net_release" [drivers/media/video/video-buf-dvb.ko] undefined!
ERROR: "dvb_frontend_detach" [drivers/media/video/video-buf-dvb.ko] undefined!
ERROR: "dvb_dmxdev_release" [drivers/media/video/video-buf-dvb.ko] undefined!
ERROR: "dvb_dmx_swfilter" [drivers/media/video/video-buf-dvb.ko] undefined!
ERROR: "dvb_net_init" [drivers/media/video/video-buf-dvb.ko] undefined!
ERROR: "dvb_dmx_release" [drivers/media/video/video-buf-dvb.ko] undefined!
ERROR: "dvb_register_adapter" [drivers/media/video/video-buf-dvb.ko] undefined!
ERROR: "dvb_dmxdev_init" [drivers/media/video/video-buf-dvb.ko] undefined!

ERROR: "mt2131_attach" [drivers/media/video/cx23885/cx23885.ko] undefined!
ERROR: "s5h1409_attach" [drivers/media/video/cx23885/cx23885.ko] undefined!

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>