dt-bindings: arm: qcom: Document QDU1000/QRU1000 SoCs and boards

Document the QDU1000 and QRU1000 SoC bindings and the boards that use
them.

Signed-off-by: Melody Olvera <quic_molvera@quicinc.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221026200429.162212-3-quic_molvera@quicinc.com