Changed every memcpy to SCA equivalent mbedtls_platform_memcpy

This makes physical attacks more difficult.
diff --git a/library/md2.c b/library/md2.c
index fbec008..8c07da9 100644
--- a/library/md2.c
+++ b/library/md2.c
@@ -180,7 +180,7 @@
         else
             fill = ilen;
 
-        memcpy( ctx->buffer + ctx->left, input, fill );
+        mbedtls_platform_memcpy( ctx->buffer + ctx->left, input, fill );
 
         ctx->left += fill;
         input += fill;
@@ -224,11 +224,11 @@
     if( ( ret = mbedtls_internal_md2_process( ctx ) ) != 0 )
         return( ret );
 
-    memcpy( ctx->buffer, ctx->cksum, 16 );
+    mbedtls_platform_memcpy( ctx->buffer, ctx->cksum, 16 );
     if( ( ret = mbedtls_internal_md2_process( ctx ) ) != 0 )
         return( ret );
 
-    memcpy( output, ctx->state, 16 );
+    mbedtls_platform_memcpy( output, ctx->state, 16 );
 
     return( 0 );
 }