qlcnic: Support atomic commands

o VFs might get scheduled out after sending a command to a PF
  and scheduled in after receiving a response. Implement a
  worker thread to handle atomic commands.

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