arm64: dts: qcom: sm8550: fix qup_spi0_cs node

The node is incomplete and doesn't need a subnode, add the missing
properties and move everything to the root of qup-spi0-cs-state node.

Fixes: ffc50b2d ("arm64: dts: qcom: Add base SM8550 dtsi")
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230308-topic-sm8550-upstream-dt-fixups-v1-2-595b02067672@linaro.org