enic: Decouple mac address registration and deregistration from port profile set operation

This patch removes VM mac address registration and deregistration code during
port profile set operation. We can delay mac address registration until
enic_open.

Signed-off-by: Roopa Prabhu <roprabhu@cisco.com>
Signed-off-by: David Wang <dwang2@cisco.com>
Signed-off-by: Christian Benvenuti <benve@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>