dt-bindings: soc: qcom: merge qcom,saw2.txt into qcom,spm.yaml

dt-bindings: soc: qcom: merge qcom,saw2.txt into qcom,spm.yaml

The Qualcomm SPM / SAW2 device is described in two bindigns files:
arm/msm/qcom,saw2.txt and soc/qcom/qcom,spm.yaml. Merge the former into
the latter, adding detailed device node description. While we are at it,
also rename qcom,spm.yaml to qcom,saw2.yaml to follow the actual
compatible used for these devices.

The regulator property is retained as is. It will be changed in the
later patches.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20240102-saw2-spm-regulator-v7-1-0472ec237f49@linaro.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>