COMPMID-431 Port OpenCL pooling layer to use fixed point

Change-Id: I6a73cd6582097aaefa83588aad789bdefdc74406
Reviewed-on: http://mpd-gerrit.cambridge.arm.com/79967
Tested-by: Kaizen <jeremy.johnson+kaizengerrit@arm.com>
Reviewed-by: Michalis Spyrou <michalis.spyrou@arm.com>
12 files changed