net: bcmgenet: remove old link state values

The PHY state machine has been fixed to only call the adjust_link
callback when the link state has changed. Therefore the old link
state variables are no longer needed to detect a change in link
state.

This commit effectively reverts
commit 5ad6e6c5 ("net: bcmgenet: improve bcmgenet_mii_setup()")

Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>