mac80211: fix authentication with iwlwifi/mvm

The original patch didn't copy the ieee80211_is_data() condition
because on most drivers the management frames don't go through
this path. However, they do on iwlwifi/mvm, so we do need to keep
the condition here.

Cc: stable@vger.kernel.org
Fixes: ce2e1ca7

 ("mac80211: Check port authorization in the ieee80211_tx_dequeue() case")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>