SSU2: Don't attempt SSU1 fallback validation on a SSU2 peer

This should actually fix the HMAC NPE

router/java/src/net/i2p/router/transport/udp/PacketHandler.java

@@ -377,6 +377,8 @@ class PacketHandler {
                         PeerState state = null;
                         int newPort = remoteHost.getPort();
                         for (PeerState ps : peers) {
+                            if (ps.getVersion() > 1)
+                                continue;
                             boolean valid = false;
                             if (_log.shouldLog(Log.WARN)) {
                                 long now = _context.clock().now();