[bluez] Call holding ofono API fix. Fixes JB#11148.

Had to change the ofono API usage when call handling related AT commands are processed. 

From ofono documentation:

                void ReleaseAndSwap()

                        Releases currently active call (0 or more) and
                        activates any currently held calls. Please note that
                        if the current call is a multiparty call, then all
                        parties in the multi-party call will be released.


                void ReleaseAndAnswer()

                        Releases currently active call (0 or more) and
                        answers the currently waiting call. Please note that
                        if the current call is a multiparty call, then all
                        parties in the multi-party call will be released.


                void HoldAndAnswer()

                        Puts the current call (including multi-party calls) on
                        hold and answers the currently waiting call. Calling
                        this function when a user already has a both Active and
                        Held calls is invalid, since in GSM a user can have
                        only a single Held call at a time.