feature: reset interface feature arc on interface deletion

When removing an interface we must reset all per-interface per-feature
arc data to ensure we do not get wrong feature arc config data when the
sw_if_index is recycled.

Type: fix

Change-Id: I8c9d850d7c62b7b77193da4258ab5fb9bdda85a6
Signed-off-by: Benoît Ganne <bganne@cisco.com>
diff --git a/src/vnet/arp/arp.c b/src/vnet/arp/arp.c
index 8b57376..e02f3d8 100644
--- a/src/vnet/arp/arp.c
+++ b/src/vnet/arp/arp.c
@@ -855,17 +855,8 @@
 vnet_arp_add_del_sw_interface (vnet_main_t * vnm, u32 sw_if_index, u32 is_add)
 {
   ethernet_arp_main_t *am = &ethernet_arp_main;
-
-  if (!is_add && sw_if_index != ~0)
-    {
-      arp_disable (am, sw_if_index);
-    }
-  else if (is_add)
-    {
-      vnet_feature_enable_disable ("arp", "arp-disabled",
-				   sw_if_index, 1, NULL, 0);
-    }
-
+  if (is_add)
+    arp_disable (am, sw_if_index);
   return (NULL);
 }