fstab: Run fsck on /persist too.

This partition gets no activity, but it can still get corrupted by
unclean shutdowns; fsck all the things

Change-Id: I60c08b5d3157e582c96f5131fd0195dd591f6fc1
(cherry picked from commit e7d388fcb097d21fa923fa2df12246e7433c1a02)