iommu/amd: Return proper error code in irq_remapping_alloc()

In the unlikely case when alloc_irq_table() is not able to return a
remap table then "ret" will be assigned with an error code. Later, the
code checks `index' and if it is negative (which it is because it is
initialized with `-1') and then then function properly aborts but
returns `-1' instead `-ENOMEM' what was intended.
In order to correct this, I assign -ENOMEM to index.
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: NJoerg Roedel <jroedel@suse.de>

drivers/iommu/amd_iommu.c

@@ -4124,7 +4124,7 @@ static int irq_remapping_alloc(struct irq_domain *domain, unsigned int virq,
 	struct amd_ir_data *data = NULL;
 	struct irq_cfg *cfg;
 	int i, ret, devid;
-	int index = -1;
+	int index;
 
 	if (!info)
 		return -EINVAL;
@@ -4166,7 +4166,7 @@ static int irq_remapping_alloc(struct irq_domain *domain, unsigned int virq,
 			WARN_ON(table->min_index != 32);
 			index = info->ioapic_pin;
 		} else {
-			ret = -ENOMEM;
+			index = -ENOMEM;
 		}
 	} else {
 		bool align = (info->type == X86_IRQ_ALLOC_TYPE_MSI);