Ignore empty optional parameters in CLCC response

Usecase:
Pair and connect with AG that sends the optional parameters
in CLCC response.

Failure:
When optional parameters in CLCC response from AG is empty,
HF client is not parsing the empty optional parameters.
User may not be see the phone number on UI properly on
hf client device.

Root cause:
AGs like iPhone sends optional parameters in the CLCC response.
HF client is returning NULL when it encounters empty optional parameters.

Fix:
Ignore empty optional parameters in CLCC Response from AG.

Change-Id: Ia90986ccc4c9c9f1a6fb3a914bc1df8b0a75ba0f