Add missing break statement in order to prevent the code from falling
through to case TEST_UNIT_READY.

Addresses-Coverity-ID: 1357338 ("Missing break in switch")
Suggested-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>