[autotest] Fix site_host close() method

BUG=chromium:281542
TEST=network_WiFi_SimpleConnect.wifi_check11b no longer hangs test_that

Change-Id: Icad06fe41046b3be39d94c2b241e16cafb0f660a
Reviewed-on: https://chromium-review.googlesource.com/167556
Tested-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Richard Barnette <jrbarnette@chromium.org>
Commit-Queue: Aviv Keshet <akeshet@chromium.org>
1 file changed