net: phy: remove genphy_c45_eee_is_active()'s is_enabled arg

All callers to genphy_c45_eee_is_active() now pass NULL as the
is_enabled argument, which means we never use the value computed
in this function. Remove the argument and clean up this function.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://patch.msgid.link/E1tJ9JC-006LIt-Ne@rmk-PC.armlinux.org.uk


Signed-off-by: Jakub Kicinski <kuba@kernel.org>