mac80211: Fix TKIP/WEP HT capability handling

There is no need to parse the AP's HT capabilities if
the STA uses TKIP/WEP cipher. This allows the rate control
module to choose the correct(legacy) rate table.

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>