net/fm: revert commit 732dfe09

This patch reverts patch 'add ft_fixup_xgec to support 3rd and 4th 10GEC'.
When dual-role MAC acts as 10G,it still uses fsl,fman-port-1g-rx/tx as before.

Signed-off-by: Shengzhou Liu <Shengzhou.Liu@freescale.com>
Acked-by: York Sun <yorksun@freescale.com>