of/address: Fix of_node memory leak in of_dma_is_coherent

Commit dabf6b36 ("of: Add OF_DMA_DEFAULT_COHERENT & select it on
powerpc") added a check to of_dma_is_coherent which returns early
if OF_DMA_DEFAULT_COHERENT is enabled. This results in the of_node_put()
being skipped causing a memory leak. Moved the of_node_get() below this
check so we now we only get the node if OF_DMA_DEFAULT_COHERENT is not
enabled.

Fixes: dabf6b36 ("of: Add OF_DMA_DEFAULT_COHERENT & select it on powerpc")
Signed-off-by: Evan Nimmo <evan.nimmo@alliedtelesis.co.nz>
Link: https://lore.kernel.org/r/20201110022825.30895-1-evan.nimmo@alliedtelesis.co.nzSigned-off-by: Rob Herring <robh@kernel.org>

drivers/of/address.c

@@ -1034,11 +1034,13 @@ int of_dma_get_range(struct device_node *np, const struct bus_dma_region **map)
  */
 bool of_dma_is_coherent(struct device_node *np)
 {
-	struct device_node *node = of_node_get(np);
+	struct device_node *node;
 
 	if (IS_ENABLED(CONFIG_OF_DMA_DEFAULT_COHERENT))
 		return true;
 
+	node = of_node_get(np);
+
 	while (node) {
 		if (of_property_read_bool(node, "dma-coherent")) {
 			of_node_put(node);