alsa_sound: Trigger immediate doRouting() on setMode() change to normal

On call hangup, this normally happens as consequence of
a setParameter call shortly after the change of mode.
However, if a stream write occurs between the mode change
and setParameter, AudioStreamOutALSA::write calls route()
which then laters causes doRouting() not to deroute voice
properly.

By triggering an immediate doRouting() on a setMode change
to normal, we remove this window of opportunity for voice
derouting to fail.

Resolves calls with mute audio on jf.  This could
theoretically show up on other platforms if the
timing conditions are right.

Change-Id: I90e98596dcb42a0b4b164fc27790c39349ea777c