[CORE] vmm_host_irq: Avoid infinite loop in vmm_host_active_irq_exec()

Currently, vmm_host_active_irq_exec() blindly loops around
till we have active host irqs. In real world, we can have
a buggy device throwing suprious interrupts which can cause
the loop to go infinite.

This patch updates the loop in vmm_host_active_irq_exec()
such that we only process 16 active host irqs at a time.

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