cxgb4: IEEE fixes for DCBx state machine

* Changes required due to 16eecd9b ("dcbnl : Fix misleading
  dcb_app->priority explanation")
* Driver was previously not aware of what DCBx version was negotiated by
  firmware, this could lead to DCB app table  in kernel or in firmware being
  populated wrong  since IEEE/CEE used different formats made clear by above
  mentioned commit
* Driver was missing a couple of state transitions that could be caused
  by other drivers that use chelsio hardware, resulting in incorrect behaviour
  (the change that addresses this also flips the state machine to switch on
   state instead of transition, hope this is okay in current window)
* Prio queue info & tsa is no longer thrown away

v2: Print DCBx state transition messages only when debug is enabled

Signed-off-by: Anish Bhatt <anish@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>