hal: support seamless speaker channels swapping

Change-Id: Ia82254cfb5d2021759f6874e7d7272c75ab91497
diff --git a/hal/platform_api.h b/hal/platform_api.h
index e50e06d..701399d 100644
--- a/hal/platform_api.h
+++ b/hal/platform_api.h
@@ -64,5 +64,5 @@
 int platform_get_usecase_index(const char * usecase);
 int platform_set_usecase_pcm_id(audio_usecase_t usecase, int32_t type, int32_t pcm_id);
 void platform_set_echo_reference(struct audio_device *adev, bool enable, audio_devices_t out_device);
-
+int platform_swap_lr_channels(struct audio_device *adev, bool swap_channels);
 #endif // AUDIO_PLATFORM_API_H