ocl: discover device properties once and simplified setting up WG-size #1541

Job	Run time
build-on-cuda (OPENMP=ON)	8m 19s
build-and-test (MPI=ON, OPENMP=ON, SMM=blas, openmpi)	4m 23s
build-on-opencl (OPENMP=ON, SMM=libxsmm)	8m 10s
build-on-rocm (OPENMP=ON, G2G=ON)	4m 2s
build-and-test (MPI=ON, OPENMP=ON, SMM=blas, mpich)	3m 57s
pre-commit	1m 19s
build-on-rocm (OPENMP=ON, G2G=OFF)	3m 49s
build-and-test (MPI=ON, OPENMP=ON, SMM=libxsmm, openmpi)	4m 56s
build-and-test (MPI=ON, OPENMP=ON, SMM=libxsmm, mpich)	4m 14s
build-and-test (MPI=ON, OPENMP=OFF, SMM=blas, openmpi)	9m 11s
build-and-test (MPI=ON, OPENMP=OFF, SMM=blas, mpich)	9m 33s
build-and-test (MPI=ON, OPENMP=OFF, SMM=libxsmm, openmpi)	9m 2s
build-and-test (MPI=ON, OPENMP=OFF, SMM=libxsmm, mpich)	9m 18s
build-and-test (MPI=OFF, OPENMP=ON, SMM=blas, openmpi)	5m 18s
build-and-test (MPI=OFF, OPENMP=ON, SMM=libxsmm, openmpi)	5m 35s
build-and-test (MPI=OFF, OPENMP=OFF, SMM=blas, openmpi)	3m 41s
build-and-test (MPI=OFF, OPENMP=OFF, SMM=libxsmm, openmpi)	3m 27s
Combine & check coverage.	1m 27s
	1h 39m 41s

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