net: phy: adjust qca8081 master/slave seed value if link down

1. The master/slave seed needs to be updated when the link can't
be created.

2. The case where two qca8081 PHYs are connected each other and
master/slave seed is generated as the same value also needs
to be considered, so adding this code change into read_status
instead of link_change_notify.

Signed-off-by: Luo Jie <luoj@codeaurora.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>