[CORE] Merge VCPU scheduling and VCPU load balancing context

For most part, we not treating load balancing and scheduling context
sperately. Also, whenever we lock load balancing, we in-turn endup
also locking scheduling context in vmm_manager_vcpu_set_hcpu().

This patch simplifies VCPU context by merging the two contexts and
removing the load balancing lock in VCPU.

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