drivers/net/igb: remove dead code (function 'igb_read_pci_cfg')

Fix this warning:

  drivers/net/igb/e1000_mac.c:54: warning: 'igb_read_pci_cfg' defined but not used
Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/igb/e1000_mac.c

@@ -50,13 +50,6 @@ void igb_remove_device(struct e1000_hw *hw)
 	kfree(hw->dev_spec);
 }
 
-static void igb_read_pci_cfg(struct e1000_hw *hw, u32 reg, u16 *value)
-{
-	struct igb_adapter *adapter = hw->back;
-
-	pci_read_config_word(adapter->pdev, reg, value);
-}
-
 static s32 igb_read_pcie_cap_reg(struct e1000_hw *hw, u32 reg, u16 *value)
 {
 	struct igb_adapter *adapter = hw->back;