backuptool: Correct supported partitions for addon.d v3

* The plan was to support odm & oem too, but it turned out
  unnecessarily complicated due to their symlink setup,
  while being most likely unused.
  The partitions were removed from the list of supported ones
  in a-only backuptool, but were forgotten in ab backuptool.

Change-Id: I58a01cdc3f5c4239048b204f3313f4bf697dd60a