Initial support for bandsteering.

Upon seeing a STA probe on 5GHz, 2.4GHz associations will be blocked
for five seconds with WLAN_STATUS_ASSOC_REJECTED_TEMPORARILY, unless
this has happened in the last ten minutes (in which case we assume the
client may be re-probing for a good reason and let it connect on
2.4Ghz).

Files containing the timestamps until which associations should be
blocked live in a directory specified by -S.

A corresonding change to /bin/wifi, which will make sure this
directory exists, will be required (otherwise the writes will fail).

Change-Id: I877be3f82ef29221dcfa5a8c410a9ea65b1deef7
6 files changed