MLBEDSW-9217: Regor: Mac Util % in performance report sometimes larger than 100%

Patch to fix mac util being reported as estimated above 100% for depth first convolutions, by accounting for sparsity and improving convolution cycle estimation.

Also removes a bug where we divide the cycle count with the amount of
wd_cores.

Change-Id: Ie565c3524f121578779e21684725b12cfe304f7f
Signed-off-by: wilisa01 <william.isaksson@arm.com>