be2net: Changes to use only priority codes allowed by f/w

Changes to use one of the priority codes allowed by CNA f/w for NIC traffic
from host. The driver gets the bit map of the priority codes allowed for
host traffic through a asynchronous message from the f/w that the driver
subscribes to.

Signed-off-by: Somnath Kotur <somnath.kotur@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>