Reset job CPU count if CPUs/task ratio increased for mem limit

If a job's CPUs/task ratio is increased due to configured MaxMemPerCPU,
then increase it's allocated CPU count in order to enforce CPU limits.
Previous logic would increase/set the cpus_per_task as needed if a
job's --mem-per-cpu was above the configured MaxMemPerCPU, but NOT
increase the min_cpus or max_cpus varilable. This resulted in allocating
the wrong CPU count.