regulator: scmi: fix of_node refcount leak in scmi_regulator_probe()

In the Linux kernel, the following vulnerability has been resolved: regulator: scmi: fix of_node refcount leak in scmi_regulator_probe() scmi_regulator_probe() calls of_find_node_by_name() which takes a reference on the returned device node. On the error path where process_scmi_regulator_of_node() fails, the function returns without calling of_node_put() on the child node, leaking the reference. Add of_node_put(np) on the error path to properly release the reference.