ipmi:ipmb: Fix refcount leak in ipmi_ipmb_probe

of_parse_phandle() returns a node pointer with refcount
incremented, we should use of_node_put() on it when done.
Add missing of_node_put() to avoid refcount leak.

Fixes: 00d93611 ("ipmi:ipmb: Add the ability to have a separate slave and master device")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Message-Id: <20220512044445.3102-1-linmq006@gmail.com>
Cc: stable@vger.kernel.org # v5.17+
Signed-off-by: Corey Minyard <cminyard@mvista.com>