ARM: shmobile: r8a7791: Add Audio DMAC peri peri devices to DT

Instantiate the Audio DMAC peri peri controllers
in the r8a7791 device tree.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>