[intfsorch] Init proxy_arp variable while adding router interface. (sonic-net#1473)

Author: Minkang-Tsai

orchagent/intfsorch.cpp

@@ -368,6 +368,7 @@ bool IntfsOrch::setIntf(const string& alias, sai_object_id_t vrf_id, const IpPre
             gPortsOrch->increasePortRefCount(alias);
             IntfsEntry intfs_entry;
             intfs_entry.ref_count = 0;
+            intfs_entry.proxy_arp = false;
             intfs_entry.vrf_id = vrf_id;
             m_syncdIntfses[alias] = intfs_entry;
             m_vrfOrch->increaseVrfRefCount(vrf_id);