net: stmmac: fix double serdes powerdown

Commit 49725ffc ("net: stmmac: power up/down serdes in
stmmac_open/release") correctly added a call to the serdes_powerdown()
callback to stmmac_release() but did not remove the one from
stmmac_remove() which leads to a doubled call to serdes_powerdown().

This can lead to all kinds of problems: in the case of the qcom ethqos
driver, it caused an unbalanced regulator disable splat.

Fixes: 49725ffc ("net: stmmac: power up/down serdes in stmmac_open/release")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Acked-by: Junxiao Chang <junxiao.chang@intel.com>
Reviewed-by: Andrew Halaney <ahalaney@redhat.com>
Tested-by: Andrew Halaney <ahalaney@redhat.com>
Link: https://lore.kernel.org/r/20230621135537.376649-1-brgl@bgdev.plSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -7457,12 +7457,6 @@ void stmmac_dvr_remove(struct device *dev)
 	netif_carrier_off(ndev);
 	unregister_netdev(ndev);
 
-	/* Serdes power down needs to happen after VLAN filter
-	 * is deleted that is triggered by unregister_netdev().
-	 */
-	if (priv->plat->serdes_powerdown)
-		priv->plat->serdes_powerdown(ndev, priv->plat->bsp_priv);
-
 #ifdef CONFIG_DEBUG_FS
 	stmmac_exit_fs(ndev);
 #endif