apmanager: make sure cfg80211 is loaded before starting

apmanager depends on cfg80211 for communication with WiFi device,
so make sure it is loaded before starting.

BUG=brillo:1168
TEST=start apmanager without error when cfg80211 is not loaded

Change-Id: I6fbcdd47d15fc367a7cfdc05bcbc1015199be102
Reviewed-on: https://chromium-review.googlesource.com/274966
Trybot-Ready: Zeping Qiu <zqiu@chromium.org>
Tested-by: Zeping Qiu <zqiu@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Commit-Queue: Zeping Qiu <zqiu@chromium.org>
1 file changed