KVM: arm64: vgic-its: Generalize use of vgic_get_irq_kref

Instead of sprinkling raw kref_get() calls everytime we cannot
do a normal vgic_get_irq(), use the existing vgic_get_irq_kref(),
which does the same thing and is paired with a vgic_put_irq().

vgic_get_irq_kref is moved to vgic.h in order to be easily shared.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

virt/kvm/arm/vgic/vgic-its.c

@@ -80,7 +80,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid)
 		 * call vgic_put_irq() on the returned pointer once it's
 		 * finished with the IRQ.
 		 */
-		kref_get(&irq->refcount);
+		vgic_get_irq_kref(irq);
 
 		goto out_unlock;
 	}