bnx2x: DCB rework

bnx2x: DCB rework

create DCB related states in function state-machine
allow handling of DCB errors from FW
allow disablement of DCB in FW, when peer disappears or error
clean up unused functions/variables as pointed by
David Binderman <dcb314@hotmail.com>

Reported-by: David Binderman <dcb314@hotmail.com>
Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 6debea870a66be4aac2e28be0e3952dad6c7fcdb)

Signed-off-by: Joe Jin <joe.jin@oracle.com>