dcbevent.h: Remove extern from function prototypes

There are a mix of function prototypes with and without extern
in the kernel sources.  Standardize on not using extern for
function prototypes.

Function prototypes don't need to be written with extern.
extern is assumed by the compiler.  Its use is as unnecessary as
using auto to declare automatic/local variables in a block.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dcbevent.h

@@ -25,9 +25,9 @@ enum dcbevent_notif_type {
 };
 
 #ifdef CONFIG_DCB
-extern int register_dcbevent_notifier(struct notifier_block *nb);
-extern int unregister_dcbevent_notifier(struct notifier_block *nb);
-extern int call_dcbevent_notifiers(unsigned long val, void *v);
+int register_dcbevent_notifier(struct notifier_block *nb);
+int unregister_dcbevent_notifier(struct notifier_block *nb);
+int call_dcbevent_notifiers(unsigned long val, void *v);
 #else
 static inline int
 register_dcbevent_notifier(struct notifier_block *nb)