MLBEDSW-9211: Add heuristic for weight buffering

 - Add simple heuristic when to enable weight buffering
since dram configurations does not always benefit from it
 - Solution to be refined based on architecture and memory
configuration

Change-Id: I501c180dd846e6886520e0a2d25c2425d7df8592
Signed-off-by: Johan Alfven <johan.alfven@arm.com>