video(DISOpticalFlow): update OpenCL implementation (#14473)

* video(DIS): add code for profiling

* video(DIS): fix test parameters

* video(DIS): simplify OpenCL kernels

- parameters -> defines
- avoid float3
- const / local scope
- improve readability, replace Kernel::set() -> args()

* video(DIS): use CV_32FC2 buffers