dt-bindings: arm: qcom: Add missing schema for IPQ4019 boards

The board bindings for IPQ4019 are undocumented. Add the missing bindings
to the schema.

Cc: Andy Gross <agross@kernel.org>
Cc: David Brown <david.brown@linaro.org>
Cc: linux-arm-msm@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/qcom.yaml

@@ -119,6 +119,11 @@ properties:
           - const: qcom,msm8996-mtp
 
       - items:
+          - enum:
+              - qcom,ipq4019-ap-dk04.1-c3
+              - qcom,ipq4019-ap-dk07.1-c1
+              - qcom,ipq4019-ap-dk07.1-c2
+              - qcom,ipq4019-dk04.1-c1
           - const: qcom,ipq4019
 
       - items: