Convert audio HAL service mk to bp and rename the service

The service supports multiple versions and its name should not be
version dependant.

For backward compatibility, keep the target name
android.hardware.audio@2.0-service (32bit only), existing
PRODUCT_PACKAGES do not have to be updated.
New products should depend on android.hardware.audio.service:32.

Additionally migrate to Android.bp, dropping support for
AUDIOSERVER_MULTILIB. Previously the HAL service architecture (32 vs 64)
would be the same as the audio server. This in not wanted as all android
audio HAL are 32 bits.

Bug: 121208203
Test: # Compare following commands before and after patch:
      find $ANDROID_PRODUCT_OUT/vendor -name 'android.hardware.audio*'|xargs file
            adb shell reboot # check device boots to UI and
      # check the HAL restarts after the audioserver is killed
      adb shell ps |grep audio; adb shell killall audioserver; adb shell ps
Change-Id: I25f41735175a6687a051ca1e5a7fee670eb8115e
Signed-off-by: Kevin Rocard <krocard@google.com>