greth_of_probe() calls greth_mdio_init(), which connects the PHY, before dev->netdev_ops is assigned. phy_attach_direct() -> phy_link_topo_add_phy() reads dev->netdev_ops through netdev_need_ops_lock() since the commit in question, so probing crashes with a NULL pointer dereference when CONFIG_NET_SHAPER is enabled.
Assign netdev_ops before the PHY attach, as was done for emac in commit 7c9f391ec89c ("net: emac: move setting of netops to fix crash").