JFS: Allow security.* xattrs to be set on symlinks

All of the different xattr namespaces have different rules.
user.* and ACL's are not allowed on symlinks, and since these were the
first xattrs implemented, I assumed there was no need to support xattrs
on symlinks.  This one-line patch should fix it.

Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>