net: phy: marvell: add comment about m88e1111_config_init_1000basex()

The comment in m88e1111_config_init_1000basex() is wrong - it claims
that Autoneg will be enabled, but this doesn't actually happen.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/E1rhos4-003yuQ-5p@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>