dt-bindings, firmware: add compatible value Intel Stratix10 service layer binding

A a compatible property value to Intel Stratix10 service layer binding
Signed-off-by: Richard Gong <richard.gong@intel.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Moritz Fischer <mdf@kernel.org>

Documentation/devicetree/bindings/firmware/intel,stratix10-svc.txt

@@ -23,7 +23,7 @@ Required properties:
 The svc node has the following mandatory properties, must be located under
 the firmware node.
 
-- compatible: "intel,stratix10-svc"
+- compatible: "intel,stratix10-svc" or "intel,agilex-svc"
 - method: smc or hvc
         smc - Secure Monitor Call
         hvc - Hypervisor Call