Error pop up is displayed when interrogating call forward menu

Service class 0 always be sent to QCRIL as long as
SERVICE_CLASS_VOICE(1) is passed in and imsphone is null
If service class 0 is passed to QCRIL, QCRIL will not send SERVICE_CLASS
TLV in qmi_voice_get_call_forwarding_req which will cause the request
failed. Change logic only pass service class 0 for SERVICE_CLASS_NONE.

Change-Id: Ie4960ea72e36ccd6dcbcad5118c26a3d3c2e313f
CRs-Fixed: 1079388