media: dvb-frontends/dvb-pll: add i2c driver support

registers the module as an i2c driver,
but keeps dvb_pll_attach() untouched for compatibility.

Signed-off-by: Akihiro Tsukada <tskd08@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/dvb-frontends/dvb-pll.h

@@ -30,6 +30,10 @@
 #define DVB_PLL_TDEE4		       18
 #define DVB_PLL_THOMSON_DTT7520X       19
 
+struct dvb_pll_config {
+	struct dvb_frontend *fe;
+};
+
 #if IS_REACHABLE(CONFIG_DVB_PLL)
 /**
  * Attach a dvb-pll to the supplied frontend structure.