If the guest issues an INT command targetting a VLPI, let's
call into the irq_set_irqchip_state() helper to make it pending
on the physical side.

This works just as well if userspace decides to inject an interrupt
using the normal userspace API...
Acked-by: NChristoffer Dall <cdall@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>