[udp6] fix 'Udp::Socket::Connect(uint16_t aPort)' (#5407)
[udp6] fix 'Udp::Socket::Connect(uint16_t aPort)' (#5407)


bukepo/openthread,bukepo/openthread,srickardti/openthread,chshu/openthread,jwhui/openthread,srickardti/openthread,srickardti/openthread,srickardti/openthread,bukepo/openthread,abtink/openthread,openthread/openthread,abtink/openthread,abtink/openthread,chshu/openthread,jwhui/openthread,chshu/openthread,openthread/openthread,bukepo/openthread,chshu/openthread,abtink/openthread,chshu/openthread,chshu/openthread,openthread/openthread,openthread/openthread,jwhui/openthread,jwhui/openthread