net: thunderx: Fix PHY autoneg for SGMII QLM mode

This patch fixes the case where there is no phydev attached
to a LMAC in DT due to non-existance of a PHY driver or due
to usage of non-stanadard PHY which doesn't support autoneg.
Changes dependeds on firmware to send correct info w.r.t
PHY and autoneg capability.

This patch also covers a case where a 10G/40G interface is used
as a 1G with convertors with Cortina PHY in between.

Signed-off-by: Thanneeru Srinivasulu <tsrinivasulu@cavium.com>
Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>