[media] ts2020: call get_rf_strength from frontend

Restore ds3000.c read_signal_strength.
Call tuner get_rf_strength from frontend read_signal_strength.
We are able to do a NULL check and doesn't limit the tuner
attach to the frontend attach area.
At the moment the lmedm04 tuner attach is stuck in frontend
attach area.

Signed-off-by: Malcolm Priestley <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/dvb-frontends/ds3000.c

···
 	return 0;
 }
 
+static int ds3000_read_signal_strength(struct dvb_frontend *fe,
+						u16 *signal_strength)
+{
+	if (fe->ops.tuner_ops.get_rf_strength)
+		fe->ops.tuner_ops.get_rf_strength(fe, signal_strength);
+
+	return 0;
+}
+
 /* calculate DS3000 snr value in dB */
 static int ds3000_read_snr(struct dvb_frontend *fe, u16 *snr)
 {
···
 	.i2c_gate_ctrl = ds3000_i2c_gate_ctrl,
 	.read_status = ds3000_read_status,
 	.read_ber = ds3000_read_ber,
+	.read_signal_strength = ds3000_read_signal_strength,
 	.read_snr = ds3000_read_snr,
 	.read_ucblocks = ds3000_read_ucblocks,
 	.set_voltage = ds3000_set_voltage,

drivers/media/dvb-frontends/m88rs2000.c

···
 static int m88rs2000_read_signal_strength(struct dvb_frontend *fe,
 	u16 *strength)
 {
-	*strength = 0;
+	if (fe->ops.tuner_ops.get_rf_strength)
+		fe->ops.tuner_ops.get_rf_strength(fe, strength);
+
 	return 0;
 }
 

drivers/media/dvb-frontends/ts2020.c

···
 
 	memcpy(&fe->ops.tuner_ops, &ts2020_tuner_ops,
 				sizeof(struct dvb_tuner_ops));
-	fe->ops.read_signal_strength = fe->ops.tuner_ops.get_rf_strength;
 
 	return fe;
 }