MSIM: changing default SIM name

* Calling it SIM instead of SUB (users don't think of them as
  subscriptions but as SIM cards);
* Changing the number to be just the slot number (it doesn't really
  make much sense to call it "SIM 01" if we can call it just
  "SIM 1");
* If we don't have an alternative carrier name but we do have a name
  to use, we should use it;
* When we're not using "SIM" as the name, but a carrier name
  (original or alternative), we don't need to identify SIMs by slots,
  so we don't add a number to the name.

Change-Id: Id5de234491f7cac063fb5e9d9f14c3aa912af01e