Update WifiP2pService.java

A p2p device on an invitation request from the peer invokes
p2p_peer command to know if the peer is a p2p device / GO.
Due to the cached entries there would be a possibility of
not getting the updated information, ending up in the wrong
negotiation with the invited peer. Thus do not rely on
p2p_peer command, rather assume that the peer is a GO on an
invitation request, provided there is no persistent network
configured.