iommu/of: Use helper functions to access dev->iommu_fwspec

Use the new helpers dev_iommu_fwspec_get()/set() to access
the dev->iommu_fwspec pointer. This makes it easier to move
that pointer later into another struct.
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/of_iommu.c

@@ -164,7 +164,7 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
 					   struct device_node *master_np)
 {
 	const struct iommu_ops *ops = NULL;
-	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
+	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
 	int err = NO_IOMMU;
 
 	if (!master_np)
@@ -208,14 +208,18 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
 		}
 	}
 
+
 	/*
 	 * Two success conditions can be represented by non-negative err here:
 	 * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons
 	 *  0 : we found an IOMMU, and dev->fwspec is initialised appropriately
 	 * <0 : any actual error
 	 */
-	if (!err)
-		ops = dev->iommu_fwspec->ops;
+	if (!err) {
+		/* The fwspec pointer changed, read it again */
+		fwspec = dev_iommu_fwspec_get(dev);
+		ops    = fwspec->ops;
+	}
 	/*
 	 * If we have reason to believe the IOMMU driver missed the initial
 	 * add_device callback for dev, replay it to get things in order.