[CORD-458] Updates ARP handler

Changes:
- SR application uses NRM;
- Adds hooks for ND protocol;
- Updates ARP handler to better leverage on NRM;
- Reworks to take into account IPv4/IPv6 together;

Change-Id: Iab55b8c5ef7d973928d8ad47e2c2a482fb9c5c8a
diff --git a/src/main/java/org/onosproject/segmentrouting/HostHandler.java b/src/main/java/org/onosproject/segmentrouting/HostHandler.java
index 82a2829..c3022ff 100644
--- a/src/main/java/org/onosproject/segmentrouting/HostHandler.java
+++ b/src/main/java/org/onosproject/segmentrouting/HostHandler.java
@@ -257,7 +257,8 @@
             PortNumber outport) {
         // Get assigned VLAN for the subnets
         VlanId outvlan = null;
-        Ip4Prefix subnet = srManager.deviceConfiguration.getPortSubnet(deviceId, outport);
+        // FIXME L2 forwarding should consider also IPv6
+        Ip4Prefix subnet = srManager.deviceConfiguration.getPortIPv4Subnet(deviceId, outport);
         if (subnet == null) {
             outvlan = VlanId.vlanId(SegmentRoutingManager.ASSIGNED_VLAN_NO_SUBNET);
         } else {