armv8: ls2080aqds: fix SGMII repeater settings

The current value to check whether the PHY was configured has dependency
on MC, it expects MC to start PCS AN, this is not true during boot up,
so it should be changed to remove the dependency.

The PHY's register space should be restore to default after accessing
extended space.

Signed-off-by: Shaohui Xie <Shaohui.Xie@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>