powerpc/iommu: Add missing of_node_put in iommu_init_early_dart

The device_node pointer is returned by of_find_compatible_node
with refcount incremented. We should use of_node_put() to avoid
the refcount leak.
Signed-off-by: Peng Wu <wupeng58@huawei.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220425081245.21705-1-wupeng58@huawei.com

arch/powerpc/sysdev/dart_iommu.c

@@ -404,9 +404,10 @@ void __init iommu_init_early_dart(struct pci_controller_ops *controller_ops)
 	}
 
 	/* Initialize the DART HW */
-	if (dart_init(dn) != 0)
+	if (dart_init(dn) != 0) {
+		of_node_put(dn);
 		return;
-
+	}
 	/*
 	 * U4 supports a DART bypass, we use it for 64-bit capable devices to
 	 * improve performance.  However, that only works for devices connected
@@ -419,6 +420,7 @@ void __init iommu_init_early_dart(struct pci_controller_ops *controller_ops)
 
 	/* Setup pci_dma ops */
 	set_pci_dma_ops(&dma_iommu_ops);
+	of_node_put(dn);
 }
 
 #ifdef CONFIG_PM