avdt_ad_write_req() function

* Function avdt_ad_write_req * Description This function is called by a CCB or SCB to send data to a * transport channel. It looks up the LCID of the channel * based on the type, CCB, and SCB (if present). Then it * passes the data to L2CA_DataWrite(). * Returns AVDT_AD_SUCCESS, if data accepted, else FALSE * AVDT_AD_CONGESTED, if data accepted and the channel is congested * AVDT_AD_FAILED, if error