Avoid calling scrollBy(0,0) on render

Usually scrollBy(0, 0) won't have any effect but when called on the
NumberPicker but, in some cases, it seems to cause an endless loop.
When called from layoutlib, this will hold the read lock causing all
operations trying to acquire the write lock to block forever.

Bug: http://b.android.com/182506
Change-Id: Ib25427d3f32d804d1c481d979795eee71fbdbc6d