Add forward definition for usecase_type_t

Fixes a build break.

Change-Id: Id0dabdc00ec46f05bca2c73674dd02d5bf2da453
diff --git a/hal/audio_hw.h b/hal/audio_hw.h
index 4963316..798d954 100644
--- a/hal/audio_hw.h
+++ b/hal/audio_hw.h
@@ -240,7 +240,7 @@
     card_status_t card_status;
 };
 
-typedef enum {
+typedef enum usecase_type_t {
     PCM_PLAYBACK,
     PCM_CAPTURE,
     VOICE_CALL,
diff --git a/hal/platform_api.h b/hal/platform_api.h
index e97975a..ebbe9d2 100644
--- a/hal/platform_api.h
+++ b/hal/platform_api.h
@@ -28,6 +28,7 @@
 };
 
 enum card_status_t;
+enum usecase_type_t;
 
 void *platform_init(struct audio_device *adev);
 void platform_deinit(void *platform);
@@ -42,7 +43,7 @@
 int platform_set_snd_device_acdb_id(snd_device_t snd_device, unsigned int acdb_id);
 int platform_get_snd_device_acdb_id(snd_device_t snd_device);
 int platform_send_audio_calibration(void *platform, snd_device_t snd_device);
-int platform_get_default_app_type_v2(void *platform, usecase_type_t type, int *app_type);
+int platform_get_default_app_type_v2(void *platform, enum usecase_type_t type, int *app_type);
 int platform_switch_voice_call_device_pre(void *platform);
 int platform_switch_voice_call_enable_device_config(void *platform,
                                                     snd_device_t out_snd_device,