Update setHotwordMode to setHotwordModeEnabled and set/clear the hotword
mode based on the boolean flag passed to setHotwordModeEnabled. This is
to meet the API requirements. Also update the references to this API.
BUG: 180419637
Test: Able to setHotwordModeEnabled from AGSA application. Confirmed
HAL receives the flag and audioSource correctly in open_input_stream.
Change-Id: Ia01e8b5f3edaeafc9617846efc247635005456a8
ab5fedc682