Try to make test_idle less racy

Reconfiguration should be synchronous, but just in case, wait
afterwords.  The second wait may be more important -- we might
still have some outstanding timer events from the previous
configuration so we should make sure that everything really has
stopped before we release builds.

Change-Id: I52a3b0c309dc87fc6a553e690286d5dae093e085
1 file changed