dt-bindings: i2c: qcom,i2c-qup: Document power-domains

Similar to qcom,geni-i2c, for i2c-qup we need to vote for performance
states on the VDDCX power domain to ensure that required clock rates
can be generated correctly.

I2C is typically used with a fixed clock rate, so a single required-opp
is sufficient without a full OPP table (unlike spi-qup for example).

Signed-off-by: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20231128-i2c-qup-dvfs-v1-1-59a0e3039111@kernkonzept.com

Documentation/devicetree/bindings/i2c/qcom,i2c-qup.yaml

@@ -52,9 +52,15 @@ properties:
       - const: default
       - const: sleep
 
+  power-domains:
+    maxItems: 1
+
   reg:
     maxItems: 1
 
+  required-opps:
+    maxItems: 1
+
 required:
   - compatible
   - clock-names
@@ -68,6 +74,7 @@ examples:
   - |
     #include <dt-bindings/clock/qcom,gcc-msm8998.h>
     #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/power/qcom-rpmpd.h>
 
     i2c@c175000 {
         compatible = "qcom,i2c-qup-v2.2.1";
@@ -82,6 +89,8 @@ examples:
         pinctrl-names = "default", "sleep";
         pinctrl-0 = <&blsp1_i2c1_default>;
         pinctrl-1 = <&blsp1_i2c1_sleep>;
+        power-domains = <&rpmpd MSM8909_VDDCX>;
+        required-opps = <&rpmpd_opp_svs_krait>;
         clock-frequency = <400000>;
 
         #address-cells = <1>;