Fman/mEMAC: mEMAC fix for 10G MAC and PHY

Fman/mEMAC: mEMAC fix for 10G MAC and PHY

1. use Payload length check disable when enable MAC;
2. add XGMII support for setting MAC interface mode;
3. only enable auto negotiation for Non-XGMII mode;
4. return 0xffff if clause 22 is used to read 10G phy_id;

Signed-off-by: Shaohui Xie <Shaohui.Xie@freescale.com>
Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
Acked-By: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: York Sun <yorksun@freescale.com>