qlcnic: Fix panic while dumping TX queues on TX timeout

o In case of non-multi TX queue mode driver does not initialize "crb_intr_mask" pointer
  and driver was accessing that un-initialized pointer while dumping TX queue.
  So dump "crb_intr_mask" only when it is initilaized.

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