Add MTL response string define

Change-Id: I96b723495e8e744c8be13761f70cdd907e850b39
Change private to pretected for MTK

Change-Id: I4bf75d85aea10a574654aaf0c959a60b52a2542b
Change RIL base command for MTK

Change-Id: Id47395de978ea255073a4e47edcb2d51bf332716