dt-bindings: mfd: qcom,spmi-pmic: Document PMC8180 and PMC8180C

Document qcom,pmc8180 and qcom,pmc8180c compatibles already used in DTS:

sc8180x-primus.dtb: pmic@1: compatible:0: 'qcom,pmc8180' is not one of ...

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Acked-by: Conor Dooley <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

Documentation/devicetree/bindings/mfd/qcom,spmi-pmic.yaml

···
           - qcom,pm8994
           - qcom,pm8998
           - qcom,pma8084
+          - qcom,pmc8180
+          - qcom,pmc8180c
           - qcom,pmd9635
           - qcom,pmi632
           - qcom,pmi8950