By default |allowedKeyMgmt| is set to WPA_PSK, however the
|preSharedKey| is not set for this WifiConfiguration. So, the new
|validate| method added in ag/2339612, will reject the network update
(rightly so, because it's an invalid configuration). So, set the key
mgmt to |NONE| to indicate that this is an open network and hence does
not need the |preSharedKey| field.
Bug: 62418044
Test: Failing test passes now.
Change-Id: If979b909f2fb7d7b4e2626b57eff407ba6a019ab
eb0e095e16