MLBEDSW-6296: Regression caused by bigger weight buffering size

- Due to that bigger weight buffer sizes are being used, there are use cases
when feature maps are evicted from SRAM, causing the total performance to drop.
- A way to improve this is to limit the memory for those weight buffer ops,
to get the feature maps back to SRAM, and see if total performance is improved.

Signed-off-by: Johan Alfven <johan.alfven@arm.com>
Change-Id: Ibfaff330677185186af9f6362dfbe04824a329f6