b43: fix crash with OpenFWWF

b43 with open firmware crashes mac80211 because
it changes the number of queues at runtime which,
while it was never really supported, now crashes
mac80211 due to the new hardware queue logic.

Fix this by detecting open vs. proprietary fw
earlier and registering with mac80211 with the
right number of queues.

Tested-by: Stefan Lippers-Hollmann <s.l-h@gmx.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Cc: stable@vger.kernel.org (depends on commit a6f38ac3)
Signed-off-by: John W. Linville <linville@tuxdriver.com>