dmaengine: remove Renesas Audio DMAC peri peri

Renesas R-Car sound (= rsnd) needs 2 DMAC which are called as
Audio DMAC (= 1st DMAC) and Audio DMAC peri peri (2nd DMAC).
And rsnd had assumed that 1st / 2nd DMACs are implemented as DMAEngine.
But, in result of DMA ML discussion, 2nd DMAC was concluded that it is
not a general purpose DMAC (2nd DMAC is for Device to Device inside
sound system). Additionally, current DMAEngine can't support Device to
Device, and we don't have correct DT bindings for it at this point.
So the easiest solution for it is that move it from DMAEngine to rsnd
driver.
Audio DMAC peri peri on DMAEngine is no longer needed. remove it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>