idmap_rfc2307: Don't stop after 30 entries

idmap_rfc2307: Don't stop after 30 entries

We start over again and again, so we need to search in the whole list.
This is a quick hack generating a bad O(n^2). The real fix is to
call idmap_rfc2307_find_map with "maps" starting at the right offset,
but that's an optimization for later when it's restructured

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12757

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Christof Schmitt <cs@samba.org>