usbaudio: allow compiling for 64-bit

Set -Wno-unused-parameter, which makes the directory warnings-clean
on 32-bit and 64-bit.
Remove LOCAL_32_BIT_ONLY.

Change-Id: I672d4ee8d9e70c75f9376ca60389af08f73166b8
diff --git a/modules/usbaudio/Android.mk b/modules/usbaudio/Android.mk
index 2acd171..2af7897 100644
--- a/modules/usbaudio/Android.mk
+++ b/modules/usbaudio/Android.mk
@@ -24,7 +24,7 @@
 	external/tinyalsa/include
 LOCAL_SHARED_LIBRARIES := liblog libcutils libtinyalsa
 LOCAL_MODULE_TAGS := optional
-LOCAL_32_BIT_ONLY := true
+LOCAL_CFLAGS := -Wno-unused-parameter
 
 include $(BUILD_SHARED_LIBRARY)