Use audio_source_t consistently

Change-Id: Ie25ddeb091646b7e24149b3b23a18ce0807e1891
diff --git a/modules/audio/audio_policy.c b/modules/audio/audio_policy.c
index bfb4c39..5fb6095 100644
--- a/modules/audio/audio_policy.c
+++ b/modules/audio/audio_policy.c
@@ -121,7 +121,7 @@
 {
 }
 
-static audio_io_handle_t ap_get_input(struct audio_policy *pol, int inputSource,
+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,