laptop-mode-tools: switch wifi support to be nl80211-only

We support only nl80211 WiFi devices; no more WEXT support:
- remove old script that used iwconfig
- add new module script that uses iw to ena/dis power save

Note this also fixes wifi power save operation for nl80211 devices as the iwconfig code never worked right due to it checking the wrong file under /sys.  This means we should now have lower latency on AC because we'll turn off power save.

TEST=gmerge to device; suspend+resume and check power save state of wlan0; also run sh -x laptop_mode auto force and verify the right things are happenig for wifi devices

Review URL:

Change-Id: Ifac0b67c7eb6663fb911be267711c44e6e8538b0
1 file changed