qlcnic: Fix loopback diagnostic test

o Adapter requires that if the port is in loopback mode no traffic should
  be flowing through that port, so on arrival of Link up AEN, do not advertise
  Link up to the stack until port is out of loopback mode

Signed-off-by: Manish Chopra <manish.chopra@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>