DMA transfer uses DVC

     DMA               DMApp
[MEM] -> [SRC] -> [DVC] -> [SSIU] -> [SSI]

     DMA               DMApp
[MEM] <- [DVC] <- [SRC] <- [SSIU] <- [SSI]
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>