Fix persisting wifi state on setWifiEnabled() call

When somebody makes a quick setWifiEnabled calls in back to back succession,
we were missing setting the last state because we were only doing that
when wifi was in a particular state from a state machine's perspective.

This was done to handle the interaction b/w airplane and wifi and was
done in the wrong way. That part is now moved to the code which detects
airplane mode changes.

In the longer term, I want to move the whole persisting code as part of
wifi state machine which is more aware of the exact states wifi is in.

Bug: 6504534
Change-Id: I452f3f4efdeb84458dcfd280269e09ffa3844f05