gianfar: ethtool: Fix refcount leak in gfar_get_ts_info

In the Linux kernel, the following vulnerability has been resolved: gianfar: ethtool: Fix refcount leak in gfar_get_ts_info The of_find_compatible_node() function returns a node pointer with refcount incremented, We should use of_node_put() on it when done Add the missing of_node_put() to release the refcount.