of: export of_platform_populate()

Without this, modules can't use this API, leading to build failures.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>

drivers/of/platform.c

@@ -462,4 +462,5 @@ int of_platform_populate(struct device_node *root,
 	of_node_put(root);
 	return rc;
 }
+EXPORT_SYMBOL_GPL(of_platform_populate);
 #endif /* CONFIG_OF_ADDRESS */