* [LITE][OPENCL] remove useless code. test=develop

* [LITE][OPENCL] finish 4 kernel and unit tests of image2d opencl elementwise_mul kernel. test=develop

* [LITE][OPENCL] Fix little bug of ASSERT. test=develop

* [LITE][OPENCL] Fix bug of channel_mul_d2 and d4. test=develop

* [LITE][OPENCL]develop basic image depthwiseconv,passed loop test,test=develop

* [LITE][OPENCL]log to vlog(4),test=develop

* [LITE][OPENCL]fix depthwise buffer conv kernel name ,test=develop

* [LITE][OPENCL] conv2d_1x1_image, choose simple kernel when in some case. for opencl ,test=develop

* [LITE][OPENCL] conv2d_1x1_image, add looptest ,test=develop

* add reshape opencl kernel && optimise conv 1x1 ,test=develop

* add reshape opencl kernel && optimise conv 1x1 &&code style ,test=develop

* add reshape opencl kernel && optimise conv 1x1 &&code style ,test=develop

[LITE][OPENCL] Add relu image2d kernel unit test, Fix conv2d_1x1, relu, layout using new Image2D Layout (#2564)

* add 3 layout for opencl image. test=develop

* add relu image2d test. test=develop

* [LITE][OPENCL] Add depthwise_conv_3x3 opencl kernel

* [LITE][OPENCL] Add depthwise_conv_3x3 opencl kernel. test=develop

* [LITE][OPENCL] Add Pool opencl kernel. test=develop

* add opencl conv1x1 image impl and unit test pass with relu & bias,
add layout_compute --> buffer2image float32 --> with unit test pass
suite checked test for more situation , test=develop

* add opencl conv1x1 image impl and unit test pass with relu & bias,
add layout_compute --> buffer2image float32 --> with unit test pass
suite checked test for more situation , test=develop

* fix white space cpp lint , test=develop

[LITE][OPENCL] Fix layout, target pass for OpenCL, add macro of CONVERT_TYPE_TO and READ/WRITE image, memory reuse in ResetLazyImage2D (#2170)

* add macro of CONVERT_TYPE_TO and READ/WRITE image. test=develop

* add data type control. test=develop

* fix io op as general layout and precision. test=develop

* Fix memory reuse strategy for opencl image2d. test=develop

* remove std::array, std::map in about opencl backend. test=develop

* [LITE][OPENCL] support image2d. test=develop

* add context changed with consider image*. test=develop

* add layout, relu image kernels. test=develop

* replace image_data with data, mutable_image_data with mutable_data, test=develop

* comment unused var. test=develop

* remove unused var. test=develop