Remove SkNx AVX code. It is not really used. Getting in the way of refactoring.

src/opts/SkOpts_avx.cpp

Index: src/opts/SkOpts_avx.cpp
diff --git a/src/opts/SkOpts_avx.cpp b/src/opts/SkOpts_avx.cpp
deleted file mode 100644
index 88021530023bc080ec9c86fa6f2088c83dfdacb8..0000000000000000000000000000000000000000
--- a/src/opts/SkOpts_avx.cpp
+++ /dev/null
@@ -1,17 +0,0 @@
-/*
- * Copyright 2015 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#include "SkOpts.h"
-#define SK_OPTS_NS sk_avx
-#include "SkXfermode_opts.h"
-
-namespace SkOpts {
-    void Init_avx() {
-        create_xfermode = sk_avx::create_xfermode;
-    }
-}
-