net: dsa: bcm_sf2: Ensure we re-negotiate EEE during after link change

In case the link change and EEE is enabled or disabled, always try to
re-negotiate this with the link partner.

Fixes: 450b05c1 ("net: dsa: bcm_sf2: add support for controlling EEE")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>