Eliminate dependencies on hardware/audio.h (trivial cases)

frameworks/av must not depend on hardware/ (except for the code
from libaudiohal that actually calls into HAL).

This CL deals with simple cases where depending on system/audio.h
is enough.

Change-Id: Ia2cb66cc8c92316ce5ab884a008d5e531263c2e4
Test: make
diff --git a/media/libaudiohal/DeviceHalLocal.h b/media/libaudiohal/DeviceHalLocal.h
index 6c15eb7..eba360c 100644
--- a/media/libaudiohal/DeviceHalLocal.h
+++ b/media/libaudiohal/DeviceHalLocal.h
@@ -17,6 +17,7 @@
 #ifndef ANDROID_HARDWARE_DEVICE_HAL_LOCAL_H
 #define ANDROID_HARDWARE_DEVICE_HAL_LOCAL_H
 
+#include <hardware/audio.h>
 #include <media/audiohal/DeviceHalInterface.h>
 
 namespace android {