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.

Fixes: abc3aeae ("fsl-rio: Add two ports and rapidio message units support")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220512123724.62931-1-linmq006@gmail.com