binwifi: Add client isolation; use on portals.

Client isolation prevents the AP from routing traffic between two
clients of a WLAN. This improves security on networks where the clients
don't need to talk to each other, like provisioning and guest networks.

Fixes b/34289885.

Change-Id: Ic9364f261adeab2225e7402c5aea2e9a12b8e407
5 files changed