Hook up r8a774a1 Audio-DMAC nodes to the IPMMU-MP.

Based on work for the r8a7795 by Magnus Damm.
Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>