Fixed coding style and added some comments to image processing operators

...jects/hpvm-tensor-rt/tensor_runtime/include/device_math.h

...m-tensor-rt/tensor_runtime/include/functional/broadcast.h

...hpvm-tensor-rt/tensor_runtime/include/functional/common.h

.../hpvm-tensor-rt/tensor_runtime/include/functional/map.cuh

...-tensor-rt/tensor_runtime/include/functional/map_typing.h

...vm-tensor-rt/tensor_runtime/include/functional/reduce.cuh

...pvm-tensor-rt/tensor_runtime/include/img_tensor_runtime.h

.../hpvm-tensor-rt/tensor_runtime/include/img_tensor_utils.h

...projects/hpvm-tensor-rt/tensor_runtime/src/device_math.cu

...s/hpvm-tensor-rt/tensor_runtime/src/img_tensor_runtime.cu

...ts/hpvm-tensor-rt/tensor_runtime/src/img_tensor_utils.cpp