hal: Convert libaudioamp to audio_amplifier HAL

Change-Id: I5113923e3cc1989f2272ea439735492c9ce4d8a3
diff --git a/hal/audio_hw.h b/hal/audio_hw.h
index 0394497..abc9804 100644
--- a/hal/audio_hw.h
+++ b/hal/audio_hw.h
@@ -22,6 +22,7 @@
 
 #include <cutils/list.h>
 #include <hardware/audio.h>
+#include <hardware/audio_amplifier.h>
 #include <tinyalsa/asoundlib.h>
 #include <tinycompress/tinycompress.h>
 
@@ -280,6 +281,7 @@
      * or other capabilities are present for the device corresponding to that usecase.
      */
     struct pcm_params *use_case_table[AUDIO_USECASE_MAX];
+    amplifier_device_t *amp;
 };
 
 int select_devices(struct audio_device *adev,