Audio policy: use SPEAKER_SAFE device for alarms and ringtones

Use AUDIO_DEVICE_OUT_SPEAKER_SAFE when available for
  STRATEGY_SONIFICATION instead of AUDIO_DEVICE_OUT_SPEAKER.
It is alrady the case for STRATEGY_SONIFICATION_RESPECTFUL
  (notifications).

Test: play an alarm on a device with SPEAKER_SAFE in the policy conf, verify routing matches mixer path
Bug: 35675592
Change-Id: I03a4f4238a1ac73165d44f72e4e587b31ec88cc5