AVDT_WriteReq() function

* Function AVDT_WriteReq * Description Send a media packet to the peer device. The stream must * be started before this function is called. Also, this * function can only be called if the stream is a SRC. * When AVDTP has sent the media packet and is ready for the * next packet, an AVDT_WRITE_CFM_EVT is sent to the * application via the control callback. The application must * wait for the AVDT_WRITE_CFM_EVT before it makes the next * call to AVDT_WriteReq(). If the applications calls * AVDT_WriteReq() before it receives the event the packet * will not be sent. The application may make its first call * to AVDT_WriteReq() after it receives an AVDT_START_CFM_EVT * or AVDT_START_IND_EVT. * The application passes the packet using the BT_HDR structure. * This structure is described in section 2.1. The offset * field must be equal to or greater than AVDT_MEDIA_OFFSET. * This allows enough space in the buffer for the L2CAP and * AVDTP headers. * The memory pointed to by p_pkt must be a GKI buffer * allocated by the application. This buffer will be freed * by the protocol stack; the application must not free * this buffer. * Returns AVDT_SUCCESS if successful, otherwise error.