mac80211: correct header length calculation

HT Control field may also be present in management frames, as defined
in 8.2.4.1.10 of 802.11-2012. Account for this in calculation of header
length.

Signed-off-by: Fred Chou <fred.chou.nd@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
1 file changed