[media] dvb-core: define general callback value for demodulator

Allow use of that general callback for demod too.

Signed-off-by: Antti Palosaari <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/dvb/dvb-core/dvb_frontend.h

···
 	void *analog_demod_priv;
 	struct dtv_frontend_properties dtv_property_cache;
 #define DVB_FRONTEND_COMPONENT_TUNER 0
+#define DVB_FRONTEND_COMPONENT_DEMOD 1
 	int (*callback)(void *adapter_priv, int component, int cmd, int arg);
 	int id;
 };