[LITE][OPENCL][Image] open depthwise spl ,test=develop (#3186)

lite/kernels/opencl/conv_image_compute.cc

@@ -98,7 +98,7 @@ void ConvImageCompute::PrepareForRun() {
         filter_image_dims[0], filter_image_dims[1], filter_image_v.data());
 
     impl_ = &ConvImageCompute::Conv2d1x1;
-// #define DEPTH_CONV_USE_SPL
+#define DEPTH_CONV_USE_SPL
 #ifdef DEPTH_CONV_USE_SPL
   } else if (filter_dims[1] == 1 && x_dims[1] == output_dims[1] &&
              kernel_h == 3 && kernel_w == 3 && groups > 1) {
@@ -126,6 +126,7 @@ void ConvImageCompute::PrepareForRun() {
              &&
              kernel_h != 3
 #endif
+#undef DEPTH_CONV_USE_SPL
              ) {
     // depth_conv2d
     kernel_func_names_.push_back("depth_conv2d");