Fixes BHV-13014

## Issue
When a moon.DatePicker is first initialized with a value, it doesn't calculate the maximum days in the selected month. As a result, navigating to the next date always displays `1` regardless of the next date.

## Fix
The logic that determined the need to calculate the max days was based on the previous implementation of IntegerPicker using Panels. This fix simplifies the logic and thereby resolves the issue.

Enyo-DCO-Signed-off-by: Ryan Duffy <ryan.duffy@lge.com>