[Tizen] Fix Logic in Stop Watch Function in Murphy Task

BUG-Tizen=TC-1670
BUG=XWALK-2557
Signed-off-by: Baptiste DURAND <baptiste.durand@open.eurogiciel.org>
Merge pull request #2494 from eurogiciel-oss/XWALK-2557

Fix Logic in Stop Watch Function in Murphy Task