wil6210: treat broadcast bssid as "disconnect all"

Hostapd request disconnect for broadcast bssid when it
wants to disconnect all stations from the AP.

Detect this and really disconnect all connected stations.

Change-Id: Ib5c874ef266115ddb532ec4f871e63ef1e030ae0
Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
Git-commit: 68682b4108f1254a34e40f516f9ab1f49b4754fc
Git-repo: https://github.com/kvalo/ath.git


Signed-off-by: Hamad Kadmany <hkadmany@codeaurora.org>