ARM: dts: r8a7743: Add audio DMAC support

Instantiate the two audio DMA controllers on the r8a7743 device tree.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>