dt-bindings: msm: dsi-phy-14nm: Document SM6125 variant

Document availability of the 14nm DSI PHY on SM6125.  Note that this
compatible uses the SoC-suffix variant, intead of postfixing an
arbitrary number without the sm/sdm portion.  The PHY is not powered by
a vcca regulator like on most SoCs, but by the MX power domain that is
provided via the power-domains property and a single corresponding
required-opps.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Patchwork: https://patchwork.freedesktop.org/patch/548979/
Link: https://lore.kernel.org/r/20230723-sm6125-dpu-v4-12-a3f287dd6c07@somainline.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Documentation/devicetree/bindings/display/msm/dsi-phy-14nm.yaml

@@ -19,6 +19,7 @@ properties:
       - qcom,dsi-phy-14nm-2290
       - qcom,dsi-phy-14nm-660
       - qcom,dsi-phy-14nm-8953
+      - qcom,sm6125-dsi-phy-14nm
 
   reg:
     items:
@@ -35,6 +36,16 @@ properties:
   vcca-supply:
     description: Phandle to vcca regulator device node.
 
+  power-domains:
+    description:
+      A phandle and PM domain specifier for an optional power domain.
+    maxItems: 1
+
+  required-opps:
+    description:
+      A phandle to an OPP node describing the power domain's performance point.
+    maxItems: 1
+
 required:
   - compatible
   - reg