ASoC: dt-bindings: rockchip: i2s-tdm: Drop rockchip,cru property

This property was only needed for a driver hack, which we can
remove. Since the bindings were not in any kernel release yet, we
are able to just drop the property instead of silently accepting
and ignoring it.

Signed-off-by: Nicolas Frattaroli <frattaroli.nicolas@gmail.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Message-Id: <20211016105354.116513-3-frattaroli.nicolas@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>