arm64: dts: renesas: #sound-dai-cells is used when simple-card

Current sound comment is indicating that #sound-dai-cells is required,
but it is needed only if board is using "simple-card".
Hence tidy up the comments.

As ulcb.dtsi and salvator-common.dtsi are already using "audio-graph",
the unneeded #sound-dai-cells are removed.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/87cz7ji418.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>