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
update cudev color conversions according to the latest changes in CPU code
increase epsilons for tests due to different optimizations (IPP vs CUDA, float vs double)