Fixes the ad-hoc network WEP key list issue.

If we configure the wep keys after creating the ibss network, the
beacons of this network will not show correctly (it still shows "key
off" in iwlist scan report). This is because we don't update the
beacon info in firmware.

Signed-off-by: Hong Liu <hong.liu@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>