Stop slow processes from killing next connection

The "killall" process was given 0.2 seconds to complete on ChromeOS
which didn't seem to be enough.  From what I can tell it was hanging
around long enough to kill the next connection, which was causing
problems in the FW test for ChromeOS.  Additionally the connections
appear to have never been closed, which compounded the problem.

This CL adds two snippets of code.  One to properly wait for the
killing process to complete instead of just a sleep(), and another
to properly close open event streams after each test.

BUG=chromium:464390
TEST=manual testing on ChromeOS and Android

Change-Id: Id81813111df1576d261fe22deec175296fcbcdab
Signed-off-by: Charlie Mooney <charliemooney@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/256371
Reviewed-by: Shyh-In Hwang <josephsih@chromium.org>
diff --git a/test_suite.py b/test_suite.py
index c47b0e6..d02f26d 100644
--- a/test_suite.py
+++ b/test_suite.py
@@ -105,6 +105,9 @@
     print
     plot_image_png = plotter.end()
 
+    print 'Closing connection with DUT... ',
+    self.touch_dev.EndEventStream()
+
     # Run the validators on these events
     snapshots = mt.process(events, protocol=self.touch_dev.protocol)
     results = test.RunAllValidators(snapshots)