[autotest] Typo fix in error message.

Fix a small error message typo, and remove one unnecessary temporary
variable.

TEST=None
BUG=None

Change-Id: I7d31790217b55b675e0fc76ab4576dacfb84202a
Reviewed-on: https://gerrit.chromium.org/gerrit/41085
Commit-Queue: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
Tested-by: Aviv Keshet <akeshet@chromium.org>
1 file changed