Telephony: Misc msim data fixes.

- Ignore PS attach events on non-dds cdma sub in
  dsds configuration.
- Don't decrement ApnContext refcount below 0.
- Don't retry DataConnection if ApnContext is disabled.
- Fake ATTACHED for cdma subscription only if cdma
  subscription is already in service.
- Release all request without any specifier if DDS is
  changed.

Change-Id: I50745b0de354c3a044c2ec9cad334d9a620f02f6