Fix : question index not working correctly on submitted survey
- use maxstep to totalsteps if already submitted
- see https://github.com/LimeSurvey/LimeSurvey/commit/c297ab1cae849ad25c00de08620c43c7e2b33bcf#diff-c60bef10a130572a2bf26fd0a9db519bR532 : we don't use lastep in last 2.05 : come back to first page.