net: phy: marvell: Ensure SGMII auto-negotiation is enabled for 88E1111

When 88E1111 is operating in SGMII mode, auto-negotiation should be enabled
on the SGMII side so that the link will come up properly with PCSes which
normally have auto-negotiation enabled. This is normally the case when the
PHY defaults to SGMII mode at power-up, however if we switched it from some
other mode like 1000Base-X, as may happen in some SFP module situations,
it may not be, particularly for modules which have 1000Base-X
auto-negotiation defaulting to disabled.

Call genphy_check_and_restart_aneg on the fiber page to ensure that auto-
negotiation is properly enabled on the SGMII interface.

Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Signed-off-by: David S. Miller <davem@davemloft.net>