Remove unnecessary local variable "size".

It should also be better for optimizing when compiling kernel.

Signed-off-by: Yan Wang <yan.wang@linux.intel.com>
Merge pull request #3517 from wangyan42164:ocl_denoising_2
mark old CUDA device layer as deprecated and remove it from doxygen documentation

add a note to use new cudev module as a replacement
minoir reorganization for CUDA doxygen groups:

move main CUDA group to modules/core/cuda.hpp