e2fsck: don't set prev after processing '..' on an inline dir

e2fsck: don't set prev after processing '..' on an inline dir

In an inline directory, the '..' entry is compacted down to just the
inode number; there is no full '..' entry.  Therefore, it makes no
sense to assign 'prev' to the fake dotdot entry we put on the stack,
as this could confuse a salvage_directory call on a corrupted next
entry into modifying stack contents (the fake dotdot entry).

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>