hal: support for sound trigger LAB and concurrency

Sound trigger lookahead buffering data is read through audio hal.
Also the audio hal has to inform sound trigger hal about concurrencies
and subsytsem restart events. Audio Hal uses proprietary interface
defined by sound trigger for communication with sound trigger hal.

Change-Id: Id344077b40b481a953769518f8a6ac0adc13b709
diff --git a/hal/platform_api.h b/hal/platform_api.h
index 85b3c4f..6b75fce 100644
--- a/hal/platform_api.h
+++ b/hal/platform_api.h
@@ -76,6 +76,9 @@
 bool platform_listen_device_needs_event(snd_device_t snd_device);
 bool platform_listen_usecase_needs_event(audio_usecase_t uc_id);
 
+bool platform_sound_trigger_device_needs_event(snd_device_t snd_device);
+bool platform_sound_trigger_usecase_needs_event(audio_usecase_t uc_id);
+
 int platform_set_snd_device_backend(snd_device_t snd_device, const char * backend);
 
 /* From platform_info_parser.c */