gianfar: ethtool: Fix refcount leak in gfar_get_ts_info

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.

Fixes: e8c33fba7e22 ("net: ethernet: gianfar_ethtool: get phc index through drvdata")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Reviewed-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Link: https://lore.kernel.org/r/20220310015313.14938-1-linmq006@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>