drivers: net: xgene: Change port init sequence

This patch rearranges the port initialization sequence as recommended by
hardware specification.  This patch also removes, mac_init() call from
xgene_enet_link_state(), as it was not required.

Signed-off-by: Iyappan Subramanian <isubramanian@apm.com>
Tested-by: Fushen Chen <fchen@apm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>