Fix WifiHandler for MSim

Commit 7c26a5cce74332bc48da9e894a835f2fe795431c attempted to fix
this issue by adding back the old code, but it needs to be a method
that can be called by MSimNetworkController. So sync it back to caf
to fix the merge issue.

Change-Id: Ifc721cbf372ec50810924d7ac6d55f54663458a1