powerpc/fsl_rio: Fix refcount leak in fsl_rio_setup

In the Linux kernel, the following vulnerability has been resolved: powerpc/fsl_rio: Fix refcount leak in fsl_rio_setup of_parse_phandle() returns a node pointer with refcount incremented, we should use of_node_put() on it when not need anymore. Add missing of_node_put() to avoid refcount leak.