dt-bindings: soundwire: qcom: Document v2.1.0 version of IP block

dt-bindings: soundwire: qcom: Document v2.1.0 version of IP block

All Qualcomm SoC Soundwire controllers are version-detectable (even
1.x), however certain unidentified quirks might be potentially needed,
so document v2.1 version used on Qualcomm SM8650 and SM8750 SoCs,
fallbacking to v2.0.

Suggested-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20250519080453.29858-2-krzysztof.kozlowski@linaro.org
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>