regulator: dt-bindings: qcom,smd-rpm: Add PM8909

Document the "qcom,rpm-pm8909-regulators" compatible for describing
the regulators available in the PM8909 PMIC (controlled via the RPM
firmware).

PM8909 is very similar to the existing PM8916 but lacks 3 of the
regulators (s3, s4 and l16).
Signed-off-by: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220623094614.1410180-3-stephan.gerhold@kernkonzept.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/qcom,smd-rpm-regulator.yaml

@@ -30,6 +30,9 @@ description:
 
   For pm8841, s1, s2, s3, s4, s5, s6, s7, s8
 
+  For pm8909, s1, s2, l1, l2, l3, l4, l5, l6, l7, l8, l9, l10, l11, l12, l13,
+  l14, l15, l17, l18
+
   For pm8916, s1, s2, s3, s4, l1, l2, l3, l4, l5, l6, l7, l8, l9, l10, l11,
   l12, l13, l14, l15, l16, l17, l18
 
@@ -78,6 +81,7 @@ properties:
       - qcom,rpm-mp5496-regulators
       - qcom,rpm-pm8226-regulators
       - qcom,rpm-pm8841-regulators
+      - qcom,rpm-pm8909-regulators
       - qcom,rpm-pm8916-regulators
       - qcom,rpm-pm8941-regulators
       - qcom,rpm-pm8950-regulators