[OPENCL][BACKEND] Avoid memory copy for MallocImage when host_ptr specified (#4153)

* [OPENCL] if specify addr , do not need to modify. avoid mem copy

* test=develop

lite/backends/opencl/target_wrapper.cc

@@ -64,10 +64,10 @@ void *TargetWrapperCL::MallocImage<float>(const size_t cl_image2d_width,
                                           void *host_ptr) {
   cl::ImageFormat img_format(CL_RGBA, GetCLChannelType(PRECISION(kFloat)));
   cl_int status;
-  cl::Image2D *cl_image =
-      new cl::Image2D(CLRuntime::Global()->context(),
-                      CL_MEM_READ_WRITE | (host_ptr ? CL_MEM_COPY_HOST_PTR
-                                                    : CL_MEM_ALLOC_HOST_PTR),
+  cl::Image2D *cl_image = new cl::Image2D(
+      CLRuntime::Global()->context(),
+      (host_ptr ? CL_MEM_READ_ONLY : CL_MEM_READ_WRITE) |
+          (host_ptr ? CL_MEM_COPY_HOST_PTR : CL_MEM_ALLOC_HOST_PTR),
       img_format,
       cl_image2d_width,
       cl_image2d_height,
@@ -88,10 +88,10 @@ void *TargetWrapperCL::MallocImage<uint16_t>(const size_t cl_image2d_width,
                                              void *host_ptr) {
   cl::ImageFormat img_format(CL_RGBA, GetCLChannelType(PRECISION(kFP16)));
   cl_int status;
-  cl::Image2D *cl_image =
-      new cl::Image2D(CLRuntime::Global()->context(),
-                      CL_MEM_READ_WRITE | (host_ptr ? CL_MEM_COPY_HOST_PTR
-                                                    : CL_MEM_ALLOC_HOST_PTR),
+  cl::Image2D *cl_image = new cl::Image2D(
+      CLRuntime::Global()->context(),
+      (host_ptr ? CL_MEM_READ_ONLY : CL_MEM_READ_WRITE) |
+          (host_ptr ? CL_MEM_COPY_HOST_PTR : CL_MEM_ALLOC_HOST_PTR),
       img_format,
       cl_image2d_width,
       cl_image2d_height,
@@ -112,10 +112,10 @@ void *TargetWrapperCL::MallocImage<int32_t>(const size_t cl_image2d_width,
                                             void *host_ptr) {
   cl::ImageFormat img_format(CL_RGBA, GetCLChannelType(PRECISION(kInt32)));
   cl_int status;
-  cl::Image2D *cl_image =
-      new cl::Image2D(CLRuntime::Global()->context(),
-                      CL_MEM_READ_WRITE | (host_ptr ? CL_MEM_COPY_HOST_PTR
-                                                    : CL_MEM_ALLOC_HOST_PTR),
+  cl::Image2D *cl_image = new cl::Image2D(
+      CLRuntime::Global()->context(),
+      (host_ptr ? CL_MEM_READ_ONLY : CL_MEM_READ_WRITE) |
+          (host_ptr ? CL_MEM_COPY_HOST_PTR : CL_MEM_ALLOC_HOST_PTR),
       img_format,
       cl_image2d_width,
       cl_image2d_height,