Go to Settings > FaceBook and turn off the Contacts app to completely disassociate your iPad Contacts app from FaceBook.
If that's not what you want, try going to Settings > Mail, Contacts, Calendars; scroll down to the Contacts settings and see if you can change the default there. The setting only shows up if there is more than one set of contacts (local or synced). I'm not sure whether this is possible for FaceBook contacts, since I've never allowed FaceBook to contaminate my Contacts.
Ok, 'contaminate' is probably too strong a word, but I kind of feel that way about FaceBook syncing with my iPad's data. Let it stay in it's own app.