[CORE] Introduce vmm_vcpu_irq_wait_resume() API

This patch adds new vmm_vcpu_irq_wait_resume() API to forcefully
resume a normal VCPU that is waiting for IRQ.

This API is extremely useful for HW-assisted PICs (such as VGIC)
because HW-assisted PICs don't require vmm_vcpu_irq_assert() and
vmm_vcpu_irq_deassert() API. On the other hand, HW-assisted PICs
can use vmm_vcpu_irq_wait_resume() to resume a VCPU if was waiting
for IRQ.

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