remove piglet: Neither 7270 v1 (04.88) nor 7270 v2 (05.22, 05.50) do have a separate bitfile for POTS and ISDN
(refs #2123)

git-svn-id: file:///var/svn/freetz/trunk@10633 149334a1-2f27-0410-a3b9-fc62619ac1e6