ASoC: dt-bindings: sound: Add DT binding for RZ/G3E sound

Add a standalone device tree binding for the Renesas RZ/G3E (R9A09G047)
sound controller.

The RZ/G3E sound IP is based on R-Car Sound but differs in several ways:
- Uses unprefixed sub-node names (ssi, ssiu, src, dvc, mix, ctu) instead
  of R-Car's rcar_sound,xxx prefixed names.
- Supports up to 5 DMA controllers per direction, allowing multiple DMA
  entries with repeated channel names in SSIU, SRC and DVC sub-nodes.
- Has 47 clocks including per-SSI ADG clocks (adg-ssi-[0-9]), SCU clocks
  (scu, scu_x2, scu_supply), SSIF supply clock, AUDMAC peri-peri clock,
  and ADG clock.
- Has 14 reset lines including SCU, ADG and AUDMAC peri-peri resets.
- SSI operates exclusively in BUSIF mode.

These differences make the RZ/G3E binding incompatible with the existing
renesas,rsnd.yaml, so it is added as a separate standalone binding with
its own $ref to dai-common.yaml.

Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://patch.msgid.link/20260525110230.4014435-2-john.madieu.xa@bp.renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: John Madieu