autotest: Remove LinuxCrosRouter and remove site_wifitest artifacts

Since we only have one router implementation, remove the hacks to
support multiple types of routers.

Since we no longer have site_wifitest, remove the interfaces it
used to call into LinuxRouter through.

While we're here, kill the |hostapd| field of LinuxRouter.  It is
a dictionary that combines static constants with fields written by
the most recently instantiated router instance.  Leave the similar
station dictionary since we don't allow multiple stations
simultaneously.  In that case, the most recently instantiated station
is the only station.

TEST=wifi_matfunc passes with these changes.
BUG=chromium:328173

Change-Id: Idf86e2932cfd71ea5d01cc79e103f5e660ff5ae6
Reviewed-on: https://chromium-review.googlesource.com/180042
Commit-Queue: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Tested-by: Christopher Wiley <wiley@chromium.org>
3 files changed