iwlwifi: 802.11n configuring hw_mode parameters to support HT in A/G

This patch fills the mac80211's ieee80211_hw_mode structures with the
needed 802.11n data needed for the new framework

Signed-off-by: Ron Rindjunsky <ron.rindjunsky@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>