net: phy: read MII_CTRL1000 in genphy_read_status only if needed

Value of MII_CTRL1000 is needed only if LPA_1000MSFAIL is set.
Therefore move reading this register.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>