of_get_child_by_name() 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: 55954f3b ("net: ethernet: bgmac: move BCMA MDIO Phy code into a separate file")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20220603133238.44114-1-linmq006@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>