dt-bindings: arm: qcom: Add compatible for oneplus,billie2 phone

oneplus,billie2 (OnePlus Nord N100) is based on QualComm Snapdragon
SM4250 SoC.

Add support for the same in dt-bindings.

Signed-off-by: Iskren Chernev <iskren.chernev@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Caleb Connolly <caleb@connolly.tech>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220919180618.1840194-4-iskren.chernev@gmail.com

Documentation/devicetree/bindings/arm/qcom.yaml

@@ -54,6 +54,8 @@ description: |
         sdm845
         sdx55
         sdx65
+        sm4250
+        sm6115
         sm6125
         sm6350
         sm7225
@@ -707,6 +709,11 @@ properties:
               - xiaomi,polaris
           - const: qcom,sdm845
 
+      - items:
+          - enum:
+              - oneplus,billie2
+          - const: qcom,sm4250
+
       - items:
           - enum:
               - sony,pdx201