dt-bindings: dvfs: Use MediaTek CPUFREQ HW as an example

Qcom CPUFREQ HW don't have the support for generic performance domains yet.
So use MediaTek CPUFREQ HW that has the support available in mainline.

This also silences the below dtschema warnings for "cpufreq-qcom-hw.yaml":

Documentation/devicetree/bindings/dvfs/performance-domain.example.dt.yaml: performance-controller@12340000: reg: [[305397760, 4096]] is too short
        From schema: Documentation/devicetree/bindings/cpufreq/cpufreq-qcom-hw.yaml
Documentation/devicetree/bindings/dvfs/performance-domain.example.dt.yaml: performance-controller@12340000: 'clocks' is a required property
        From schema: Documentation/devicetree/bindings/cpufreq/cpufreq-qcom-hw.yaml
Documentation/devicetree/bindings/dvfs/performance-domain.example.dt.yaml: performance-controller@12340000: 'clock-names' is a required property
        From schema: Documentation/devicetree/bindings/cpufreq/cpufreq-qcom-hw.yaml
Documentation/devicetree/bindings/dvfs/performance-domain.example.dt.yaml: performance-controller@12340000: '#freq-domain-cells' is a required property
        From schema: Documentation/devicetree/bindings/cpufreq/cpufreq-qcom-hw.yaml
Documentation/devicetree/bindings/dvfs/performance-domain.example.dt.yaml: performance-controller@12340000: '#performance-domain-cells' does not match any of the regexes: 'pinctrl-[0-9]+'
        From schema: Documentation/devicetree/bindings/cpufreq/cpufreq-qcom-hw.yaml

Cc: Hector Yuan <hector.yuan@mediatek.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Documentation/devicetree/bindings/dvfs/performance-domain.yaml

@@ -52,10 +52,16 @@ additionalProperties: true
 
 examples:
   - |
-    performance: performance-controller@12340000 {
-        compatible = "qcom,cpufreq-hw";
-        reg = <0x12340000 0x1000>;
-        #performance-domain-cells = <1>;
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        performance: performance-controller@11bc00 {
+            compatible = "mediatek,cpufreq-hw";
+            reg = <0 0x0011bc10 0 0x120>, <0 0x0011bd30 0 0x120>;
+
+            #performance-domain-cells = <1>;
+        };
     };
 
     // The node above defines a performance controller that is a performance