audio flinger: pass mixer configuration when opening an audio output

Add the possibility for audio policy manager to indicate a mixer
audio configuration (channel mask, format, sampling rate)
different from the audio HAL stream configuration when opening an
output stream with IAudioflinger::openOutput().

Bug: 188502620
Test: atest audiopolicy_tests

Change-Id: I0b4eaa9cd3e5574b75e3b914c854f97c104ca07e
diff --git a/services/audiopolicy/service/AudioPolicyService.h b/services/audiopolicy/service/AudioPolicyService.h
index 3b77ed8..c0fbde5 100644
--- a/services/audiopolicy/service/AudioPolicyService.h
+++ b/services/audiopolicy/service/AudioPolicyService.h
@@ -659,7 +659,8 @@
         // The audio policy manager can check if the proposed parameters are suitable or not and act accordingly.
         virtual status_t openOutput(audio_module_handle_t module,
                                     audio_io_handle_t *output,
-                                    audio_config_t *config,
+                                    audio_config_t *halConfig,
+                                    audio_config_base_t *mixerConfig,
                                     const sp<DeviceDescriptorBase>& device,
                                     uint32_t *latencyMs,
                                     audio_output_flags_t flags);