Read both vendor.audio_hal.* and audio_hal.* sysprops

Starting from Q-launching devices, all vendor-defined sysprops should be
prefixed with "vendor.". To support such new devices as well as old
devices where the renamining isn't required, audio HAL is using both
properties: vendor.audio_hal.* is read first and then fall backs to
audio_hal.*.

Bug: b/138278883
Test: play some audio
Test: run VtsTrebleSysProp

Change-Id: I15158467f81ac99c36c40f6ca0a6c00cbca7fb24