dt-bindings: arm: msm: kpss-acc: Make the optional reg truly optional

The description of reg[1] says that register is optional. Adjust
minItems to make it truly optional.

Fixes: 4260ddfb ("dt-bindings: arm: msm: Convert and split kpss-acc driver Documentation to yaml")
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230627-topic-more_bindings-v1-9-6b4b6cd081e5@linaro.orgSigned-off-by: Bjorn Andersson <andersson@kernel.org>

Documentation/devicetree/bindings/power/qcom,kpss-acc-v2.yaml

@@ -21,6 +21,7 @@ properties:
     const: qcom,kpss-acc-v2
 
   reg:
+    minItems: 1
     items:
       - description: Base address and size of the register region
       - description: Optional base address and size of the alias register region