e2fsck: Fix check for hidden quota files

e2fsck: Fix check for hidden quota files

Currently e2fsck always incorrectly detects that quota inodes
need to be hidden (even if they are already hidden) and
modifies the superblock unnecessarily. This patch fixes the
check for hidden quota files and avoids modifying the
filesystem if quota inodes are already hidden.
Also, zero-out the old quota inode so that next fsck scan
doesn't complain.

Signed-off-by: Aditya Kali <adityakali@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>