[CORE] vmm_host_irq: Add APIs for access to state of routed interrupts

For pass-through device access, we need explicit access to state
of routed interrupts. This is required for devices that need to
ensure that device interrupt is in-active when guest is reset.

This patch adds needed APIs and infrastructure in vmm_host_irq
for access to state of routed interrupts.

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