1. Add the function for command descriptor preparation which will be used only by BAM DMA and it will form the DMA descriptors containing command elements 2. DMA_PREP_CMD flag should be used for forming command DMA descriptors Reviewed-by: Archit Taneja <architt@codeaurora.org> Signed-off-by: Abhishek Sahu <absahu@codeaurora.org> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>