Process complete AT cmd response.

Usecase:
1. Enable hf client role and connect with AG.
2. Receive an incoming call and accept from hf client.
3. End call from hf client.
4. Repeat the steps few times.

Failure:
UI is not updated with proper call status although
call is active.

Root cause:
When OK is received as part of AT command response,
application is not updated for it. This caused response
state mismatch in application and hence queue was not
cleared properly.

Fix:
Parse complete AT command response and update application
accordingly.

Change-Id: I8cb2362369b209903700e87330ed2a3e3052b188