BACKPORT: cfg80211: Add airtime statistics and settings

This adds TX airtime statistics to the cfg80211 station dump (to go along
with the RX info already present), and adds a new parameter to set the
airtime weight of each station. The latter allows userspace to implement
policies for different stations by varying their weights.

Signed-off-by: Toke Hiland-Jrgensen <toke@toke.dk>
[rmanohar@codeaurora.org: fixed checkpatch warnings]
Signed-off-by: Rajkumar Manoharan <rmanohar@codeaurora.org>
[move airtime weight != 0 check into policy]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

BUG=b:131197056
TEST=Wifi stress and latency under load test

(cherry picked from commit 36647055)

Resloved conflicts in:
include/net/cfg80211.h
include/uapi/linux/nl80211.h
net/wireless/nl80211.c

Signed-off-by: Kan Yan <kyan@google.com>

Change-Id: I893461f6cfefecf347ebeb676a65f8eaec102739
Reviewed-on: https://chromium-review.googlesource.com/1636898


Tested-by: Kan Yan <kyan@google.com>
Tested-by: Kan Yan <kyan@chromium.org>
Commit-Ready: Kan Yan <kyan@google.com>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Julan Hsu <julanhsu@google.com>
Reviewed-by: Kan Yan <kyan@chromium.org>