Fix wifi tethering.

The new link-status netlink monitor is a bit chatty and we were getting race conditions.
The wl0.1 soft-ap interface was getting created, but in the off state.  We would report
it available (link-added always reports it) causing wifi to start tethering, but then
we'd sometimes get a link-status-down notification and a link-status-up, causing wifi
to freak out with these two requests.

The simple fix was to not listen to the new link-status notifications.  This should be
redesigned in the future.
bug:4983942

Change-Id: Ica4f34d8bf2a07fc19b35a1e15283a7f8022165e