Fix an error when executing run_tests.sh

In the recent commit I1473fe4da96aecd0b3b0bf3a3ec1e3e87039271b , the
coverage option was introduced. But there are a few typos in the shell
script.
This commit fixes it.

Change-Id: Iecdd72f730c0f0971424ca48e6f122481493b1ee
Closes-Bug: #1268808
Merge "Fix an error when executing run_tests.sh"