Call start only when scroll position is actually changing.

There is unnecessary onScrollStart call in DataGridList render time.
DataGridList is reset itself when it is rendered and call scrollTo(0,0).
The scrollTo is calling doScrollStart without checking the position changes.
So, it is fires onScrollStart but there is no onScrollStop because it is not actually scrolling.

Fixing http://jira2.lgsvl.com/browse/BHV-11027 and http://hlm.lge.com/qi/browse/WEBOSLCD13-85658

DCO-1.1-Signed-Off-By: Kunmyon Choi kunmyon.choi@lge.com
After discussion with @KunmyonChoi, we are leaving the conditional as-is to allow for scroll events to be fired in other cases, even if the position has not changed, as some apps are relying on events in these cases to load more data, etc.