reiserfs: Fix warning and inode leak when deleting inode with xattrs

After commit 21d8a15a

 (lookup_one_len: don't accept . and ..) reiserfs
started failing to delete xattrs from inode. This was due to a buggy
test for '.' and '..' in fill_with_dentries() which resulted in passing
'.' and '..' entries to lookup_one_len() in some cases. That returned
error and so we failed to iterate over all xattrs of and inode.

Fix the test in fill_with_dentries() along the lines of the one in
lookup_one_len().

Reported-by: Pawel Zawora <pzawora@gmail.com>
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>