ClientModeImpl: add logs to debug null BSSID in L2ConnectedState

BSSID shouldn't be null in L2ConnectedState. null BSSID results
in a crash in LinkProbeManager.updateConnectionStats().

Add null check before calling LinkProbeManager, and log a wtf
to help debug the issue.

Bug: 179792830
Test: compiles
Change-Id: I6a9d233ff64fdf086fa6249857849320dfb8c0ec
1 file changed