audio_remote_submix: allow compiling for 64-bit

Fix a few 64-bit warnings and set -Wno-unused-parameter, which makes
the directory warnings-clean on 32-bit and 64-bit.
Remove LOCAL_32_BIT_ONLY.

Change-Id: I6a2183b5bb0cdf438a04de967995da7b1e2e3854
diff --git a/modules/audio_remote_submix/Android.mk b/modules/audio_remote_submix/Android.mk
index d718c76..90da396 100644
--- a/modules/audio_remote_submix/Android.mk
+++ b/modules/audio_remote_submix/Android.mk
@@ -26,6 +26,7 @@
 LOCAL_SHARED_LIBRARIES := liblog libcutils libutils libnbaio
 LOCAL_STATIC_LIBRARIES := libmedia_helper
 LOCAL_MODULE_TAGS := optional
-LOCAL_32_BIT_ONLY := true
+LOCAL_CFLAGS := -Wno-unused-parameter
+
 include $(BUILD_SHARED_LIBRARY)