BHV-12132: DatePicker: 'Day' suddenly Loops then Hangs when 'Month' Wraps Around

### Issue:
The original bug fixed itself, possibly due to changes in scroller. This commit fixes a related issue (the max value of the day picker is wrongly initialized) discovered when investigating the original bug.

### Fix:
update max when month and/or year change, and when the old date value is null

Enyo-DCO-1.1-Signed-off-by: Krishna Rangarajan <krishna.rangarajan@lge.com>