if pl->mac_ops->mac_finish() failed, phylink_err should use
"mac_finish" instead of "mac_prepare".

Fixes: b7ad14c2 ("net: phylink: re-implement interface configuration with PCS")
Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>