[CORE] vmm_vcpu_irq: improve locking for vcpu irqs

We have per-VCPU spin lock for VCPU irqs to protect the members of
virtual irq related info.

This patch fixes usage of the VCPU irqs spin lock by making sure
that lock is not held when VCPU irq functions call someother function
elsewhere. This will avoid potential deadlocks because the external
function that is being called might use spin lock or other locks or
may even preempt.

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