[media] dib7000: export just one symbol

Exporting multiple symbols don't work as it causes compilation
breakages, due to the way dvb_attach() works.

This were reported several times, like:

   drivers/built-in.o: In function `cxusb_dualdig4_rev2_tuner_attach':
>> cxusb.c:(.text+0x27d4b5): undefined reference to `dib7000p_get_i2c_master'
   drivers/built-in.o: In function `dib7070_set_param_override':
   cxusb.c:(.text+0x27d5a5): undefined reference to `dib0070_wbd_offset'
>> cxusb.c:(.text+0x27d5be): undefined reference to `dib7000p_set_wbd_ref'
   drivers/built-in.o: In function `dib7070_tuner_reset':
>> cxusb.c:(.text+0x27d5f9): undefined reference to `dib7000p_set_gpio'
   drivers/built-in.o: In function `cxusb_dualdig4_rev2_frontend_attach':
>> cxusb.c:(.text+0x27df5c): undefined reference to `dib7000p_i2c_enumeration'

In this specific report:
	CONFIG_DVB_USB_CXUSB=y
	CONFIG_DVB_DIB7000P=m

But the same type of bug can happen if:
	CONFIG_DVB_DIB7000P=m
and one of the bridge drivers is compiled builtin (cxusb, cx23885-dvb
and/or dib0700).

As a bonus, dib7000p won't be loaded anymore if the device uses
a different frontend, reducing the memory footprint.

Tested with Hauppauge Nova-TD (2 frontends).

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
diff --git a/drivers/media/usb/dvb-usb/cxusb.c b/drivers/media/usb/dvb-usb/cxusb.c
index e81a2fd..6acde5e 100644
--- a/drivers/media/usb/dvb-usb/cxusb.c
+++ b/drivers/media/usb/dvb-usb/cxusb.c
@@ -1070,8 +1070,15 @@
 	.hostbus_diversity = 1,
 };
 
+struct dib0700_adapter_state {
+	int (*set_param_save)(struct dvb_frontend *);
+	struct dib7000p_ops dib7000p_ops;
+};
+
 static int cxusb_dualdig4_rev2_frontend_attach(struct dvb_usb_adapter *adap)
 {
+	struct dib0700_adapter_state *state = adap->priv;
+
 	if (usb_set_interface(adap->dev->udev, 0, 1) < 0)
 		err("set interface failed");
 
@@ -1079,14 +1086,17 @@
 
 	cxusb_bluebird_gpio_pulse(adap->dev, 0x02, 1);
 
-	if (dib7000p_i2c_enumeration(&adap->dev->i2c_adap, 1, 18,
-				     &cxusb_dualdig4_rev2_config) < 0) {
+	if (!dvb_attach(dib7000p_attach, &state->dib7000p_ops))
+		return -ENODEV;
+
+	if (state->dib7000p_ops.i2c_enumeration(&adap->dev->i2c_adap, 1, 18,
+				       &cxusb_dualdig4_rev2_config) < 0) {
 		printk(KERN_WARNING "Unable to enumerate dib7000p\n");
 		return -ENODEV;
 	}
 
-	adap->fe_adap[0].fe = dvb_attach(dib7000p_init, &adap->dev->i2c_adap, 0x80,
-			      &cxusb_dualdig4_rev2_config);
+	adap->fe_adap[0].fe = state->dib7000p_ops.init(&adap->dev->i2c_adap, 0x80,
+					      &cxusb_dualdig4_rev2_config);
 	if (adap->fe_adap[0].fe == NULL)
 		return -EIO;
 
@@ -1095,7 +1105,10 @@
 
 static int dib7070_tuner_reset(struct dvb_frontend *fe, int onoff)
 {
-	return dib7000p_set_gpio(fe, 8, 0, !onoff);
+	struct dvb_usb_adapter *adap = fe->dvb->priv;
+	struct dib0700_adapter_state *state = adap->priv;
+
+	return state->dib7000p_ops.set_gpio(fe, 8, 0, !onoff);
 }
 
 static int dib7070_tuner_sleep(struct dvb_frontend *fe, int onoff)
@@ -1110,10 +1123,6 @@
 	.clock_khz = 12000,
 };
 
-struct dib0700_adapter_state {
-	int (*set_param_save) (struct dvb_frontend *);
-};
-
 static int dib7070_set_param_override(struct dvb_frontend *fe)
 {
 	struct dtv_frontend_properties *p = &fe->dtv_property_cache;
@@ -1128,7 +1137,7 @@
 	case BAND_UHF: offset = 550; break;
 	}
 
-	dib7000p_set_wbd_ref(fe, offset + dib0070_wbd_offset(fe));
+	state->dib7000p_ops.set_wbd_ref(fe, offset + dib0070_wbd_offset(fe));
 
 	return state->set_param_save(fe);
 }
@@ -1136,8 +1145,14 @@
 static int cxusb_dualdig4_rev2_tuner_attach(struct dvb_usb_adapter *adap)
 {
 	struct dib0700_adapter_state *st = adap->priv;
-	struct i2c_adapter *tun_i2c =
-		dib7000p_get_i2c_master(adap->fe_adap[0].fe,
+	struct i2c_adapter *tun_i2c;
+
+	/*
+	 * No need to call dvb7000p_attach here, as it was called
+	 * already, as frontend_attach method is called first, and
+	 * tuner_attach is only called on sucess.
+	 */
+	tun_i2c = st->dib7000p_ops.get_i2c_master(adap->fe_adap[0].fe,
 					DIBX000_I2C_INTERFACE_TUNER, 1);
 
 	if (dvb_attach(dib0070_attach, adap->fe_adap[0].fe, tun_i2c,