ifdef usage of legacy audio enum conversion

Without this, devices compiling from source using this HAL layer
as a static whole library will break as they already use the new enum.

Change-Id: I710dbc8b013edd5e59a04a0956c69b49da35b5ba

Conflicts:
	audio/audio_hw_hal.cpp
Add support Moto gb libaudio

Conflicts:
	audio/Android.mk
	audio/audio_hw_hal.cpp
	include/hardware_legacy/AudioHardwareInterface.h