dt-bindings: misc: qcom,fastrpc: add compute iommus

The children of FastRPC have either one or two IOMMUs in existing DTS
(SM8150, SM8450 and others).
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220909125403.803158-3-krzysztof.kozlowski@linaro.orgSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/misc/qcom,fastrpc.yaml

@@ -70,6 +70,10 @@ patternProperties:
       reg:
         maxItems: 1
 
+      iommus:
+        minItems: 1
+        maxItems: 2
+
       qcom,nsessions:
         $ref: /schemas/types.yaml#/definitions/uint32
         default: 1