Properly handle upgrade scenarios.

- Set SIM color if unset before (after upgrade)
  [NB: This could also be done in the telephony provider, but would
       require duplicating the getUnusedColor() logic]
- If we had a display name at some point, only overwrite it with new
  carrier names, but not with the generic "CARD x" string

Change-Id: I05457f5da8cd6218be7b25736c8c322b17cb97c5