dt-bindings: qcom,pdc: Add compatible for sc7180

Add the compatible string for sc7180 SoC from Qualcomm.
Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20191108092824.9773-8-rnayak@codeaurora.org

Documentation/devicetree/bindings/interrupt-controller/qcom,pdc.txt

@@ -17,7 +17,8 @@ Properties:
 - compatible:
 	Usage: required
 	Value type: <string>
-	Definition: Should contain "qcom,<soc>-pdc"
+	Definition: Should contain "qcom,<soc>-pdc" and "qcom,pdc"
+		    - "qcom,sc7180-pdc": For SC7180
 		    - "qcom,sdm845-pdc": For SDM845
 
 - reg: