MKLDNN elementwise_mul: Check if AVX512 is available

test=develop

paddle/fluid/operators/elementwise_mul_mkldnn_op.cc

@@ -136,10 +136,13 @@ class ElementwiseMulMKLDNNKernel : public framework::OpKernel<T> {
     UpdateDataFormat(ctx, (Tensor*)x, "x_data_format");
     UpdateDataFormat(ctx, (Tensor*)y, "y_data_format");
 
+    Xbyak::util::Cpu cpu;
+    const bool is_avx512_enabled = cpu.has(Xbyak::util::Cpu::tAVX512F);
     const bool are_dims_divisable = !(x_int_dims[1] % 16);
     const bool is_x_format_correct = x->format() == memory::format::nChw16c;
     const bool is_y_format_correct = y->format() == memory::format::nc;
-    if (is_x_format_correct && is_y_format_correct && are_dims_divisable) {
+    if (is_x_format_correct && is_y_format_correct && are_dims_divisable &&
+        is_avx512_enabled) {
       int pre, n, post;
       get_mid_dims(x_dims, y_dims_untrimmed, axis, &pre, &n, &post);