atl1c: disable L1/L0s when link detected

Disable L1/L0s when link detected. We enable L1/L0s when link connected
before, but there is some hareware error on some platform. So just diable
this feature when link connected. This feature is about power saving.

Signed-off-by: Jie Yang <jie.yang@atheros.com>
Signed-off-by: David S. Miller <davem@davemloft.net>