copybit: Avoid NEON instructions in s/w converter on 64bit

NEON instructions in software converter are specifically written
for 32 bit ARM architecture. Do not compile them on 64 bit arch.

Change-Id: I1dbac24df519e00a2cc125b35cbd3bc520188457
diff --git a/libcopybit/software_converter.cpp b/libcopybit/software_converter.cpp
index 71e685e..9ea8767 100644
--- a/libcopybit/software_converter.cpp
+++ b/libcopybit/software_converter.cpp
@@ -60,7 +60,7 @@
     unsigned char* oldChroma = (unsigned char*)(hnd->base + y_size);
     memcpy((char *)yv12_handle->base,(char *)hnd->base,y_size);
 
-#ifdef __ARM_HAVE_NEON
+#if defined(__ARM_HAVE_NEON) && !defined(__aarch64__)
    /* interleave */
     if(!chromaPadding) {
         unsigned char * t1 = newChroma;