[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>

drivers/media/dvb-frontends/si21xx.h

@@ -1,6 +1,7 @@
 #ifndef SI21XX_H
 #define SI21XX_H
 
+#include <linux/kconfig.h>
 #include <linux/dvb/frontend.h>
 #include "dvb_frontend.h"
 
@@ -12,8 +13,7 @@ struct si21xx_config {
 	int min_delay_ms;
 };
 
-#if defined(CONFIG_DVB_SI21XX) || \
-		(defined(CONFIG_DVB_SI21XX_MODULE) && defined(MODULE))
+#if IS_ENABLED(CONFIG_DVB_SI21XX)
 extern struct dvb_frontend *si21xx_attach(const struct si21xx_config *config,
 						struct i2c_adapter *i2c);
 #else