ASoC: rsnd: Support unprefixed DT node names for RZ/G3E

ASoC: rsnd: Support unprefixed DT node names for RZ/G3E

The RZ/G3E device tree binding uses standard unprefixed node names
("ssi", "ssiu", "src", "dvc", "mix", "ctu") instead of the legacy
"rcar_sound," prefixed names used by R-Car bindings.

Convert rsnd_parse_of_node() from a macro into a function that tries
the legacy prefixed name first, then falls back to the unprefixed name
by stripping the "rcar_sound," prefix. This makes the driver work
transparently with both old and new bindings.

While at it, update the related comments in dma.c, ssi.c and ssiu.c
that reference the hardcoded "rcar_sound,ssiu" / "rcar_sound,ssi"
names to note that the driver now accepts both the prefixed and the
unprefixed forms.

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/20260525110230.4014435-18-john.madieu.xa@bp.renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>