i40e: Use new 40G speeds

The kernel has added SPEED_40000 for ethtool.
Go ahead and use the new #define.

Change-ID: Ic7e16e5c9e91085afe539f11ee1b7668adc4d0ef
Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_ethtool.c

@@ -356,8 +356,7 @@ static void i40e_get_settings_link_up(struct i40e_hw *hw,
 	/* Set speed and duplex */
 	switch (link_speed) {
 	case I40E_LINK_SPEED_40GB:
-		/* need a SPEED_40000 in ethtool.h */
-		ethtool_cmd_speed_set(ecmd, 40000);
+		ethtool_cmd_speed_set(ecmd, SPEED_40000);
 		break;
 	case I40E_LINK_SPEED_20GB:
 		ethtool_cmd_speed_set(ecmd, SPEED_20000);