arm64: dts: renesas: r8a77965-salvator-x(s): Enable HDMI sound

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Jacopo Mondi <jacopo+renesas@jmondi.org> # Salvator-XS
[geert: Preserve sort order]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>