Move channel expansion/contraction functions to audio_utils/channels.h/.c

Change-Id: I967a062f6c1cb5ae6acb6e92f4f3df00a0336733
diff --git a/modules/usbaudio/Android.mk b/modules/usbaudio/Android.mk
index 2af7897..89c498b 100644
--- a/modules/usbaudio/Android.mk
+++ b/modules/usbaudio/Android.mk
@@ -21,8 +21,9 @@
 LOCAL_SRC_FILES := \
 	audio_hw.c
 LOCAL_C_INCLUDES += \
-	external/tinyalsa/include
-LOCAL_SHARED_LIBRARIES := liblog libcutils libtinyalsa
+	external/tinyalsa/include \
+	$(call include-path-for, audio-utils)
+LOCAL_SHARED_LIBRARIES := liblog libcutils libtinyalsa libaudioutils
 LOCAL_MODULE_TAGS := optional
 LOCAL_CFLAGS := -Wno-unused-parameter