ixgbe: use ETQF filter name instead of magic number

This patch removes a magic number that was used for the ETQF used for
filtering L2 ptp packets and replaces it with the supplied define that
previously existed. The intent is to clarify that this filter is already
set aside for L2 1588 work.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c

@@ -704,14 +704,14 @@ int ixgbe_ptp_hwtstamp_ioctl(struct ixgbe_adapter *adapter,
 	/* Store filter value for later use */
 	adapter->rx_hwtstamp_filter = config.rx_filter;
 
-	/* define ethertype filter for timestamped packets */
+	/* define ethertype filter for timestamping L2 packets */
 	if (is_l2)
-		IXGBE_WRITE_REG(hw, IXGBE_ETQF(3),
+		IXGBE_WRITE_REG(hw, IXGBE_ETQF(IXGBE_ETQF_FILTER_1588),
 				(IXGBE_ETQF_FILTER_EN | /* enable filter */
 				 IXGBE_ETQF_1588 | /* enable timestamping */
 				 ETH_P_1588));     /* 1588 eth protocol type */
 	else
-		IXGBE_WRITE_REG(hw, IXGBE_ETQF(3), 0);
+		IXGBE_WRITE_REG(hw, IXGBE_ETQF(IXGBE_ETQF_FILTER_1588), 0);
 
 #define PTP_PORT 319
 	/* L4 Queue Filter[3]: filter by destination port and protocol */