net: netcp: remove call to netif_carrier_(on/off) for MAC to Phy interface

Currently when interface type is MAC to Phy, netif_carrier_(on/off)
is called which is not needed as Phy lib already updates the carrier
status to net stack. This is needed only for other interface types

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>