net: dsa: qca8k: do not cache unneeded EEE fields

The qca8k driver is currently caching a bitfield of the supported member
of a ethtool_eee private structure, which is unused.

Only the eee_enabled field of the private ethtool_eee copy is updated,
thus using p->advertised and p->lp_advertised is also erroneous.

Remove the usage of these private ethtool_eee members and only rely on
phy_ethtool_get_eee to assign the eee_active member.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>