Telephony: Fix DcSwitchStateMachine hung issue.

Issues seems to occur as follow..
1. Config CT + CMCC.
2. DDS is present on CMCC.
3. remove/deactivate CMCC SIm.
4. reboot the device.
5. Since the DDS SIM was removed/deactivated above, DDS was
   attempted on CT SIM, which was rejected by modem. So now
   modem is having DDS set on CMCC sub but Android remembers
   DDS on CT sub.
6. At the bootup android tries to set the DDS on CT sub.
7. Modem reports data in service on CMCC sub.
8. DcSwitchSTateMachine of CMCC sub ignores the data in
   service event on non-dds-cmcc sub.
7. Primary card feature kicks in and tries to move the DDS on
   CMCC.
8. DcSwitchStatemachine request ATTACH and wait for data-in-service
   to be reported.
9. Modem is already in service on CMCC and hence
   DcSwitchStateMachine does not get further event to progress the
   state-machine to ATTACHED state and hence the issue.

Fix:
- Upon ALLOW_DATA(true) success event in ATTACHING state
  move to ATTACHED state if data is already REGISTERED.

Change-Id: I29e6d80f315a8d9593e0bd59553a561492057f2d