iwlwifi: fix reserved2 field in iwl4965_addsta

reserved2 field in "struct iwl4965_addsta_cmd" is __le16.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>