net: bcmgenet: apply MII configuration in bcmgenet_open()

In case an interface has been brought down before entering S3, and then
brought up out of S3, all the initialization done during
bcmgenet_probe() by bcmgenet_mii_init() calling bcmgenet_mii_config() is
just lost since register contents are restored to their reset values.

Re-apply this configuration anytime we call bcmgenet_open() to make sure
our port multiplexer is properly configured to match the PHY interface.

Since we are now calling bcmgenet_mii_config() everytime bcmgenet_open()
is called, make sure we only print the message during initialization
time not to pollute the console.

Fixes: b6e978e5 ("net: bcmgenet: add suspend/resume callbacks")
Fixes: 1c1008c7 ("net: bcmgenet: add main driver file")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>