mac80211: don't attempt to reorder multicast frames

commit 051a41fa4ee14f5c39668f0980973b9a195de560 upstream.

Multicast frames can't be transmitted as part of an aggregation
session (such a session couldn't even be set up) so don't try to
reorder them. Trying to do so would cause the reorder to stop
working correctly since multicast QoS frames (as transmitted by
the Aruba APs this was found with) would cause sequence number
confusion in the buffer.

Reported-by: Blaise Gassend <blaise@suitabletech.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>