services: Enable runtime logging in AudioService

Add runtime logging in AudioService based on isLoggable,
which helps to debug easily without recompiling services.

To use it :

add log.tag.AS.AudioService.Mode=LOG_LEVEL
in the build.prop and reboot.

Test: compile and enable flags to check logs
Bug: 440323751
Flag: NONE logging improvement

Change-Id: Ie8c018c0ee2bfc3d3547e25343acafeb6e47bb93