util: Optimal preview size picks smaller-than-display size in case of tie

This fixes the case when 1600x1200 was selected over 1280x960 on a
Nexus 5 (display size 1920x1080); both preview sizes were equally close,
but the larger one was arbitrarily winning out.

Bug: 17216523
Change-Id: I163c29d5f46ad1b8b44825424c5202eb87855048
1 file changed