dt-bindings: arm: cpus: Add apple,firestorm & icestorm compatibles

These are the CPU cores in the "Apple Silicon" M1 SoC.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Hector Martin <marcan@marcan.st>

Documentation/devicetree/bindings/arm/cpus.yaml

@@ -85,6 +85,8 @@ properties:
 
   compatible:
     enum:
+      - apple,icestorm
+      - apple,firestorm
       - arm,arm710t
       - arm,arm720t
       - arm,arm740t