[media] DVB: dvb_frontend: check function pointers on reinitialize

Signed-off-by: Andreas Oberritter <obi@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/dvb-core/dvb_frontend.c

@@ -577,12 +577,10 @@ restart:
 
 		if (fepriv->reinitialise) {
 			dvb_frontend_init(fe);
-			if (fepriv->tone != -1) {
+			if (fe->ops.set_tone && fepriv->tone != -1)
 				fe->ops.set_tone(fe, fepriv->tone);
-			}
-			if (fepriv->voltage != -1) {
+			if (fe->ops.set_voltage && fepriv->voltage != -1)
 				fe->ops.set_voltage(fe, fepriv->voltage);
-			}
 			fepriv->reinitialise = 0;
 		}