Centering FUL fixes b/7480608

A simple one-line change to center FUL horizontally.  This looked
really bad on tablets when the charging text was showing as FUL was
obviously off-center compared to the text.  It was also off-center
on phones, which looked particularly bad when going to the backup.

Change-Id: Id0e3039a67c9bb746a8c9948e82ff87b6c815e1b