[media] mn88472: calculate the IF register values

Add xtal as a configuration parameter so it can be used
in the IF register value calculation.

Signed-off-by: Benjamin Larsson <benjamin@southpole.se>
Reviewed-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/dvb-frontends/mn88472.h

@@ -33,6 +33,12 @@ struct mn88472_config {
 	 * DVB frontend.
 	 */
 	struct dvb_frontend **fe;
+
+	/*
+	 * Xtal frequency.
+	 * Hz
+	 */
+	u32 xtal;
 };
 
 #endif