Fix Wifi state not updated while connecting

Wifi no longer updates ConnectivityService
regarding Wifi state during a connection,
so calling ConnectivityManager#getNetworkInfo
returns an invalid state. Instead, simply call
updateNetworkInfo(null), which will reuse the
last NetworkInfo object, while updating the RSSI
values.

Bug: 150188453
Test: verified in SUW
Change-Id: I0c5ebd8ebc07030e128ae913d81dbf56489239a2