igb: Cleanups to remove unneeded extern declaration

This patch fixes WARNING:AVOID_EXTERNS found by checkpatch file check.
Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igb/igb_main.c

@@ -114,7 +114,6 @@ static const struct pci_device_id igb_pci_tbl[] = {
 
 MODULE_DEVICE_TABLE(pci, igb_pci_tbl);
 
-void igb_reset(struct igb_adapter *);
 static int igb_setup_all_tx_resources(struct igb_adapter *);
 static int igb_setup_all_rx_resources(struct igb_adapter *);
 static void igb_free_all_tx_resources(struct igb_adapter *);