Ext4utils: Fix unused parameters

Refactor code so that parameters are not unused and the debug code
is always at least checked (and in non-debug cases compiled away).

Bug: 18632512

(cherry picked from commit 7ec740fee7356dd72918c9b9fd0a91276356673b)

Change-Id: I0e1eedae97a6edceb1771e10e6ec82c641ba9c5e
1 file changed