[media] tda18212: prepare for I2C client conversion

We need carry pointer to frontend via config struct
(I2C platform_data ptr) when I2C model is used. Add that pointer
first in order to keep build unbreakable during conversion.
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/tuners/tda18212.h

@@ -37,6 +37,11 @@ struct tda18212_config {
 	u16 if_dvbc;
 	u16 if_atsc_vsb;
 	u16 if_atsc_qam;
+
+	/*
+	 * pointer to DVB frontend
+	 */
+	struct dvb_frontend *fe;
 };
 
 #if IS_ENABLED(CONFIG_MEDIA_TUNER_TDA18212)