dt-bindings: spmi: convert QCOM PMIC SPMI bindings to yaml

Convert Qualcomm PMIC SPMI binding to yaml format.

Signed-off-by: David Heidelberg <david@ixit.cz>
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211227170151.73116-1-david@ixit.cz