net: ixp4xx_hss: drop kfree for memory allocated with devm_kzalloc

It's not necessary to free memory allocated with devm_kzalloc
and using kfree leads to a double free.

Fixes: 35aefaad ("net: ixp4xx_hss: Convert to use DT probing")
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/wan/ixp4xx_hss.c

@@ -1508,7 +1508,6 @@ static int ixp4xx_hss_remove(struct platform_device *pdev)
 	unregister_hdlc_device(port->netdev);
 	free_netdev(port->netdev);
 	npe_release(port->npe);
-	kfree(port);
 	return 0;
 }