mondrianwifi: fstab: Fix typo (default => defaults)

Using "default" instead of "defaults" mostly works except it fails
when mounting an ext4 partition (external SD or USB-OTG).

Change-Id: I3aba3cb17c3eff258f521aa4ba5fe18e9cf34765
Revert "mondrianwifi: Equate /system/vendor/firmware /system/etc/firmware"

This reverts commit d46caaf676ab3b3ce52ca6cd25a197edd2f5e8fe.

Change-Id: Ie2107b7a3516643b2816c464a836ffb3d211490d