[media] cx24120: fix strict checkpatch-errors

This patches fixes all checkpatch-errors.
Even the ones created --strict.

Signed-off-by: Patrick Boettcher <patrick.boettcher@posteo.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
diff --git a/drivers/media/dvb-frontends/cx24120.h b/drivers/media/dvb-frontends/cx24120.h
index e5748aa..f097042 100644
--- a/drivers/media/dvb-frontends/cx24120.h
+++ b/drivers/media/dvb-frontends/cx24120.h
@@ -43,13 +43,12 @@
 };
 
 #if IS_REACHABLE(CONFIG_DVB_CX24120)
-extern struct dvb_frontend *cx24120_attach(
-	const struct cx24120_config *config,
-	struct i2c_adapter *i2c);
+struct dvb_frontend *cx24120_attach(const struct cx24120_config *config,
+				    struct i2c_adapter *i2c);
 #else
-static inline struct dvb_frontend *cx24120_attach(
-	const struct cx24120_config *config,
-	struct i2c_adapter *i2c)
+static inline
+struct dvb_frontend *cx24120_attach(const struct cx24120_config *config,
+				    struct i2c_adapter *i2c)
 {
 	pr_warn("%s: driver disabled by Kconfig\n", __func__);
 	return NULL;