net: dsa: fix wrong pointer passed to PTR_ERR() in dsa_port_phylink_create()

Fix wrong pointer passed to PTR_ERR() in dsa_port_phylink_create() to print
error message.

Fixes: cf5ca4dd

 ("net: dsa: don't leave dangling pointers in dp->pl when failing")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>