reiserfs: deal with NULL xattr root w/ xattrs disabled

This avoids an Oops in open_xa_root that can occur when deleting a file
with xattrs disabled.  It assumes that the xattr root will be there, and
that is not guaranteed.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --cc fs/reiserfs/super.c
Simple merge

diff --cc fs/reiserfs/xattr.c
Simple merge