e1000e: bad short packets received when jumbos enabled on 82579

When short packets are received with jumbos enabled on 82579, they can be
interpreted to have a receive address that does not match any configured
address.  This is due to a hardware bug that can be worked around by
reducing the number of IPG octets added when the packet is transferred from
the PHY to the MAC.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000e/ich8lan.c

@@ -1578,7 +1578,7 @@ s32 e1000_lv_jumbo_workaround_ich8lan(struct e1000_hw *hw, bool enable)
 		ret_val = e1e_wphy(hw, PHY_REG(776, 20), data);
 		if (ret_val)
 			goto out;
-		ret_val = e1e_wphy(hw, PHY_REG(776, 23), 0xFE00);
+		ret_val = e1e_wphy(hw, PHY_REG(776, 23), 0xF100);
 		if (ret_val)
 			goto out;
 		e1e_rphy(hw, HV_PM_CTRL, &data);