Use audio_channel_mask_t consistently

Change-Id: Ib832c0b707b1e0b82adf4ab3d4d18a2dc459d240
diff --git a/modules/audio/audio_policy.c b/modules/audio/audio_policy.c
index ee95e92..a44ea77 100644
--- a/modules/audio/audio_policy.c
+++ b/modules/audio/audio_policy.c
@@ -98,7 +98,7 @@
                                        audio_stream_type_t stream,
                                        uint32_t sampling_rate,
                                        audio_format_t format,
-                                       uint32_t channels,
+                                       audio_channel_mask_t channelMask,
                                        audio_output_flags_t flags)
 {
     return 0;
@@ -124,7 +124,7 @@
 static audio_io_handle_t ap_get_input(struct audio_policy *pol, audio_source_t inputSource,
                                       uint32_t sampling_rate,
                                       audio_format_t format,
-                                      uint32_t channels,
+                                      audio_channel_mask_t channelMask,
                                       audio_in_acoustics_t acoustics)
 {
     return 0;