iommu/amd: Prevent NULL pointer dereference

Dereferencing irq_data before checking it for NULL is suboptimal.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/amd/iommu.c

@@ -3731,8 +3731,8 @@ static int irq_remapping_alloc(struct irq_domain *domain, unsigned int virq,
 
 	for (i = 0; i < nr_irqs; i++) {
 		irq_data = irq_domain_get_irq_data(domain, virq + i);
-		cfg = irqd_cfg(irq_data);
-		if (!irq_data || !cfg) {
+		cfg = irq_data ? irqd_cfg(irq_data) : NULL;
+		if (!cfg) {
 			ret = -EINVAL;
 			goto out_free_data;
 		}