pybind USE_OP_DEVICE_KERNEL(XXX, CUDNN) automatically

[luotao1]

Paddle/paddle/fluid/operators/CMakeLists.txt

Lines 170 to 172 in 6752b06

	file(APPEND ${pybind_file} "USE_OP_DEVICE_KERNEL(conv2d, CUDNN);\n")
	file(APPEND ${pybind_file} "USE_OP_DEVICE_KERNEL(pool2d, CUDNN);\n")
	file(APPEND ${pybind_file} "USE_OP_DEVICE_KERNEL(conv2d_transpose, CUDNN);\n")

Can we pybind USE_OP_DEVICE_KERNEL(XXX, CUDNN) automatically?

Otherwise, when we add new device kernel like MKLDNN, the operators/CMakeLists.txt will be very longer and many if-else likes:
https://github.com/PaddlePaddle/Paddle/pull/8451/files#diff-2f55eef7dba89ace8cdce5f5726dbee6R171-R195 in #8451