[media] dvb-frontends: use IS_ENABLED

Instead of checking everywhere there for 3 symbols, use instead
IS_ENABLED macro.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/dvb-frontends/s921.h b/drivers/media/dvb-frontends/s921.h
index f220d82..8d5e2a6 100644
--- a/drivers/media/dvb-frontends/s921.h
+++ b/drivers/media/dvb-frontends/s921.h
@@ -17,6 +17,7 @@
 #ifndef S921_H
 #define S921_H
 
+#include <linux/kconfig.h>
 #include <linux/dvb/frontend.h>
 
 struct s921_config {
@@ -24,8 +25,7 @@
 	u8 demod_address;
 };
 
-#if defined(CONFIG_DVB_S921) || (defined(CONFIG_DVB_S921_MODULE) \
-	&& defined(MODULE))
+#if IS_ENABLED(CONFIG_DVB_S921)
 extern struct dvb_frontend *s921_attach(const struct s921_config *config,
 					   struct i2c_adapter *i2c);
 extern struct i2c_adapter *s921_get_tuner_i2c_adapter(struct dvb_frontend *);