drivers: net: xgene: fix: Use GPIO to get link status

The link value reported by the link status register is not
reliable when no SPF module inserted. This patchset fixes this
issue by using GPIO to determine the link status.

Signed-off-by: Iyappan Subramanian <isubramanian@apm.com>
Signed-off-by: Quan Nguyen <qnguyen@apm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>