Hold on data-stall recovery logic during voice call on other sub.

- Data stall may get falsely triggered if there is a voice call on
  other sub and data is dormant on current data subscription.
- As part of recovery, telephony may bring-down the PDP or even reset
  the modem.
- Do not proceed the data-stall logic if there is an active voice
  call on any of the subscriptions.

Change-Id: I4e8c233fb581c79c7f8419adac6aecbe3c148179
CRs-Fixed: 781407