arp: check for manually added proxy-arp entries

When manually adding neighbor entries for proxy-arp, those will be
fib-adj entries. Check for proxy-arp instead of dropping immediately.

Type: improvement

Change-Id: Id311159f2966c99719dc2a67d4d2bc92bf366029
Signed-off-by: Benoît Ganne <bganne@cisco.com>
diff --git a/src/vnet/arp/arp.c b/src/vnet/arp/arp.c
index ce3eb39..d39d48e 100644
--- a/src/vnet/arp/arp.c
+++ b/src/vnet/arp/arp.c
@@ -556,7 +556,7 @@
 		  error0 =
 		    arp_learn (sw_if_index0, &arp0->ip4_over_ethernet[0]);
 		}
-	      goto drop;
+	      goto next_feature;
 	    case ARP_DST_FIB_CONN:
 	      /* destination is connected, continue to process */
 	      break;