powerpc/cell: Add missing of_node_put() in iommu.c

In cell_iommu_init_disabled(), hold the reference returned by
of_find_node_by_name() and use it to call of_node_put() for reference
balance.
Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220701144949.252364-2-windhl@126.com

arch/powerpc/platforms/cell/iommu.c

@@ -720,8 +720,10 @@ static int __init cell_iommu_init_disabled(void)
 	cell_disable_iommus();
 
 	/* If we have no Axon, we set up the spider DMA magic offset */
-	if (of_find_node_by_name(NULL, "axon") == NULL)
+	np = of_find_node_by_name(NULL, "axon");
+	if (!np)
 		cell_dma_nommu_offset = SPIDER_DMA_OFFSET;
+	of_node_put(np);
 
 	/* Now we need to check to see where the memory is mapped
 	 * in PCI space. We assume that all busses use the same dma