COMPMID-564: Implement reference and CL/NEON validation for CustomConvolution (output S16)

Change-Id: Ic099336f558e994210a59e14ec0171fae68ccb80
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/116663
Reviewed-by: Pablo Tello <pablo.tello@arm.com>
Tested-by: Jenkins <bsgcomp@arm.com>
5 files changed