of: fix sparse warnings in of_find_next_cache_node

sparse gives a warning that 'handle' is not a __be32:

../drivers/of/base.c:2261:61: warning: incorrect type in argument 1 (different base types)
../drivers/of/base.c:2261:61:    expected restricted __be32 const [usertype] *p
../drivers/of/base.c:2261:61:    got unsigned int const [usertype] *[assigned] handle

We could just change the type, but the code can be improved by using
of_parse_phandle instead of open coding it with of_get_property and
of_find_node_by_phandle.
Signed-off-by: NRob Herring <robh@kernel.org>

drivers/of/base.c

@@ -2250,15 +2250,14 @@ EXPORT_SYMBOL_GPL(of_console_check);
  */
 struct device_node *of_find_next_cache_node(const struct device_node *np)
 {
-	struct device_node *child;
-	const phandle *handle;
+	struct device_node *child, *cache_node;
 
-	handle = of_get_property(np, "l2-cache", NULL);
-	if (!handle)
-		handle = of_get_property(np, "next-level-cache", NULL);
+	cache_node = of_parse_phandle(np, "l2-cache", 0);
+	if (!cache_node)
+		cache_node = of_parse_phandle(np, "next-level-cache", 0);
 
-	if (handle)
-		return of_find_node_by_phandle(be32_to_cpup(handle));
+	if (cache_node)
+		return cache_node;
 
 	/* OF on pmac has nodes instead of properties named "l2-cache"
 	 * beneath CPU nodes.