[CORE] vmm_loadbal: More improvements to crude balancer

Currently, the crude loadbalancer is not able to correctly
determine worst hcpu if more than one hcpu have 100% cpu
utilization.

This patch improves the meaning of "worst hcpu" for curde
loadbalancer, as follows:
1. A worst hcpu is hcpu with maximum cpu utilization
2. If more than one hcpu have maximum cpu utilization
   then hcpu with more active VCPUs is consided worst.

The above mentioned improvement in "worst hcpu" semantics
helps crude loadbalancer perform better when 2 or more
hcpu are 100% utilized by helping pick more appropriate
"worst hcpu".

Signed-off-by: Anup Patel <anup@brainfault.org>