powerpc: Use device_type helpers to access the node type

Remove directly accessing device_node.type pointer and use the
accessors instead. This will eventually allow removing the type
pointer.

Replace the open coded iterating over child nodes with
for_each_child_of_node() while we're here.

Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/setup-common.c

@@ -687,7 +687,7 @@ int check_legacy_ioport(unsigned long base_port)
 		return ret;
 	parent = of_get_parent(np);
 	if (parent) {
-		if (strcmp(parent->type, "isa") == 0)
+		if (of_node_is_type(parent, "isa"))
 			ret = 0;
 		of_node_put(parent);
 	}