devmode-test: update --binhost style

The shell dev_install accepts '--binhost <URI>' but the new C++
version accepts '--binohst=<URL>'.  Update the invocation here.

BUG=chromium:935142
TEST=running devinstall_test.py uses the right binhost

Change-Id: I6cf62c69cfb0942b50a3f86b5b9cf85e1539ad03
Reviewed-on: https://chromium-review.googlesource.com/1799783
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
diff --git a/devmode-test/devinstall_test.py b/devmode-test/devinstall_test.py
index 69c6aed..cd5f027 100755
--- a/devmode-test/devinstall_test.py
+++ b/devmode-test/devinstall_test.py
@@ -145,7 +145,7 @@
       logging.info('Running dev install in the vm.')
       self.device.RunCommand(
           ['bash', '-l', '-c',
-           '"/usr/bin/dev_install --yes --binhost %s"' % self.binhost])
+           '"/usr/bin/dev_install --yes --binhost=%s"' % self.binhost])
 
       logging.info('Verifying that python works on the image.')
       # crbug.com/955147: /usr/local/bin/python symlink doesn't exist.