arm64: dts: renesas: ebisu: Enable Audio

This patch enables Audio for the Ebisu board on R8A77990 SoC.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
[simon: rebased]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>