Use audio_channel_mask_t more places

Use it in AudioSystem::getOutput(), AudioSystem::getInput(),
IAudioPolicyService::getOutput(), IAudioPolicyService::getInput(),
and various other places in AudioFlinger.

Not done: AudioTrack and OutputDescriptor.

Change-Id: I70e83455820bd8f05dafd30c63d636c6a47cd172
diff --git a/services/audioflinger/AudioPolicyService.h b/services/audioflinger/AudioPolicyService.h
index b4924fc..7c6fa74 100644
--- a/services/audioflinger/AudioPolicyService.h
+++ b/services/audioflinger/AudioPolicyService.h
@@ -64,7 +64,7 @@
     virtual audio_io_handle_t getOutput(audio_stream_type_t stream,
                                         uint32_t samplingRate = 0,
                                         audio_format_t format = AUDIO_FORMAT_DEFAULT,
-                                        uint32_t channels = 0,
+                                        audio_channel_mask_t channelMask = 0,
                                         audio_output_flags_t flags =
                                                 AUDIO_OUTPUT_FLAG_NONE);
     virtual status_t startOutput(audio_io_handle_t output,
@@ -77,7 +77,7 @@
     virtual audio_io_handle_t getInput(audio_source_t inputSource,
                                     uint32_t samplingRate = 0,
                                     audio_format_t format = AUDIO_FORMAT_DEFAULT,
-                                    uint32_t channels = 0,
+                                    audio_channel_mask_t channelMask = 0,
                                     int audioSession = 0);
     virtual status_t startInput(audio_io_handle_t input);
     virtual status_t stopInput(audio_io_handle_t input);