omx: prevent input port enable/disable for software codecs

Bug: 29421804
Change-Id: Iba1011e9af942a6dff7f659af769a51e3f5ba66f

OMX_ERRORTYPE SimpleSoftOMXComponent::emptyThisBuffer(
        OMX_BUFFERHEADERTYPE *buffer) {
    sp<AMessage> msg = new AMessage(kWhatEmptyThisBuffer, mHandler);
    msg->setPointer("header", buffer);
    msg->post();

 return OMX_ErrorNone;
}

OMX_ERRORTYPE SimpleSoftOMXComponent::emptyThisBuffer(
        OMX_BUFFERHEADERTYPE *buffer) {
    sp<AMessage> msg = new AMessage(kWhatEmptyThisBuffer, mHandler);
    msg->setPointer("header", buffer);
    msg->post();

 return OMX_ErrorNone;
}
