Telephony: Handle race condition during sim deactivation.

Issue:
- config L/W/G + 1x
- DDS sim is deactivated. DDS is being auto switched to 1x sub.
- Modem/qcril reports 1x subscription in service before QtiDctController
  gets a chance to processRequests or could request EVENT_CONNECT to
  DcSwitchStateMachine.
- During this window both of the DcSwitchStateMachines are IDLE.
- ATTACHED event is handled by 1x DcSwitchStateMachine and it moves from IDLE
  to ATTACHED state without sending ALLOW_DATA(T) to modem.

Solution:
- Since the race conditon is due to the fact the both DcSwitchStateMachine
  are IDLE and ATTACHED event is handled before EVENT_CONNECT. The solution is
  to defer the ATTACHED event IFF DcSwitchStateMachine is IDLE and belongs
  to DDS sub also transition to ATTACHING state.
- As we enter into ATTACHING state we would send out ALLOW_DATA(T) and
  the deferred event ATTACHED would be handled in this state which would kick us
  to ATTACHED state.This way modem and telephony both would be in sync with respect
  to DDS movement for this usecase.

Change-Id: I8c7e0ea4d8a7c919703ef22c5df1b94902ab830c