[media] dvb_frontend.h: get rid of unused tuner params/states

There are several tuner_param values that aren't by any driver or core:
	DVBFE_TUNER_TUNERSTEP
	DVBFE_TUNER_IFFREQ
	DVBFE_TUNER_REFCLOCK
	DVBFE_TUNER_IQSENSE
	DVBFE_TUNER_DUMMY

Several of those correspond to the values at the tuner_state
struct with is also only initialized by not used anyware:
	u32 tunerstep;
	u32 ifreq;
	u32 refclock;

It doesn't make sense to keep anything at the kABI that it is
not used. So, get rid of them.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>