cxgb4: do DCB state reset in couple of places

reset the driver's DCB state in couple of places
where it was missing.

Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>