ChooseDataSim: Use the extra data from the intent to validate the sub

Instead of waiting for the telephony stack to catch up to the default,
take advantage of the fact that the intent already carries the ID as
an extra.

Also, we were using slotId and phoneId interchangeably, and they're not
the same thing. While it's likely they'll match on a freshly reset
phone, don't assume that. Index everything to subId for consistency.

Ref CYNGNOS-3126

Change-Id: Ibcd767d0124b05d669886190f5d9a98f1a6e5bd7