Use audio_in_acoustics_t consistently

Change-Id: Id49ad9631092db8c9ace0f45db918f708b0b32e9
diff --git a/include/hardware/audio_policy.h b/include/hardware/audio_policy.h
index edf6a68..0dd8b49 100644
--- a/include/hardware/audio_policy.h
+++ b/include/hardware/audio_policy.h
@@ -293,7 +293,7 @@
                                     uint32_t *pSamplingRate,
                                     audio_format_t *pFormat,
                                     uint32_t *pChannels,
-                                    uint32_t acoustics);
+                                    audio_in_acoustics_t acoustics);
 
     /* closes an audio input */
     int (*close_input)(void *service, audio_io_handle_t input);