igb: support RX flow classification by ethertype

This patch is meant to allow for RX network flow classification to insert
and remove ethertype filter by ethtool

Example:
Add an ethertype filter:
$ ethtool -N eth0 flow-type ether proto 0x88F8 action 2

Show all filters:
$ ethtool -n eth0
4 RX rings available
Total 1 rules

Filter: 15
	Flow Type: Raw Ethernet
	Src MAC addr: 00:00:00:00:00:00 mask: FF:FF:FF:FF:FF:FF
	Dest MAC addr: 00:00:00:00:00:00 mask: FF:FF:FF:FF:FF:FF
	Ethertype: 0x88F8 mask: 0x0
	Action: Direct to queue 2

Delete the filter by location:
$ ethtool -N delete 15

Signed-off-by: Ruhao Gao <ruhao.gao@ni.com>
Signed-off-by: Gangfeng Huang <gangfeng.huang@ni.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/igb/igb_ptp.c b/drivers/net/ethernet/intel/igb/igb_ptp.c
index 336c103..66dfa20 100644
--- a/drivers/net/ethernet/intel/igb/igb_ptp.c
+++ b/drivers/net/ethernet/intel/igb/igb_ptp.c
@@ -998,12 +998,12 @@
 
 	/* define ethertype filter for timestamped packets */
 	if (is_l2)
-		wr32(E1000_ETQF(3),
+		wr32(E1000_ETQF(IGB_ETQF_FILTER_1588),
 		     (E1000_ETQF_FILTER_ENABLE | /* enable filter */
 		      E1000_ETQF_1588 | /* enable timestamping */
 		      ETH_P_1588));     /* 1588 eth protocol type */
 	else
-		wr32(E1000_ETQF(3), 0);
+		wr32(E1000_ETQF(IGB_ETQF_FILTER_1588), 0);
 
 	/* L4 Queue Filter[3]: filter by destination port and protocol */
 	if (is_l4) {