irqchip/gic-v3-its: Add VPE invalidation hook

When a guest issues a INVALL command targetting a collection, it must
be translated into a VINVALL for the VPE that has this collection.

This patch implements a hook that offers this functionallity to the
hypervisor.

Reviewed-by: Thomas Gleixner <[e-mail]>
Signed-off-by: Marc Zyngier <[e-mail]>

drivers/irqchip/irq-gic-v3-its.c

···
 		its_vpe_deschedule(vpe);
 		return 0;
 
+	case INVALL_VPE:
+		its_send_vinvall(vpe);
+		return 0;
+
 	default:
 		return -EINVAL;
 	}