intel: 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>

drivers/net/ethernet/intel/igbvf/igbvf.h

@@ -312,17 +312,17 @@ enum igbvf_state_t {
 extern char igbvf_driver_name[];
 extern const char igbvf_driver_version[];
 
-extern void igbvf_check_options(struct igbvf_adapter *);
-extern void igbvf_set_ethtool_ops(struct net_device *);
+void igbvf_check_options(struct igbvf_adapter *);
+void igbvf_set_ethtool_ops(struct net_device *);
 
-extern int igbvf_up(struct igbvf_adapter *);
-extern void igbvf_down(struct igbvf_adapter *);
-extern void igbvf_reinit_locked(struct igbvf_adapter *);
-extern int igbvf_setup_rx_resources(struct igbvf_adapter *, struct igbvf_ring *);
-extern int igbvf_setup_tx_resources(struct igbvf_adapter *, struct igbvf_ring *);
-extern void igbvf_free_rx_resources(struct igbvf_ring *);
-extern void igbvf_free_tx_resources(struct igbvf_ring *);
-extern void igbvf_update_stats(struct igbvf_adapter *);
+int igbvf_up(struct igbvf_adapter *);
+void igbvf_down(struct igbvf_adapter *);
+void igbvf_reinit_locked(struct igbvf_adapter *);
+int igbvf_setup_rx_resources(struct igbvf_adapter *, struct igbvf_ring *);
+int igbvf_setup_tx_resources(struct igbvf_adapter *, struct igbvf_ring *);
+void igbvf_free_rx_resources(struct igbvf_ring *);
+void igbvf_free_tx_resources(struct igbvf_ring *);
+void igbvf_update_stats(struct igbvf_adapter *);
 
 extern unsigned int copybreak;