COMPMID-834 Fix arm_compute_nightly_validation getting killed

Changed CLReductionOperationKernel: Now each kernel computes
a 2D slice instead of 1D. This reduces the memory footprint
from around 1.6Gb for a 4k input image to a few Mb, which was
caused by the __local memory and was probably the cause for this bug.

Change-Id: I71ac71ff09b041c945a134177600f0f3475e48cf
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/117835
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>
Tested-by: Anthony Barbier <anthony.barbier@arm.com>
2 files changed