dt-bindings: phy: qcom,qmp-ufs: add missing SM8450 clock

Add the missing "qref" clock used by the SM8450 UFS QMP PHY to the
binding.

Note that the "qref" clock was added to sm8450.dtsi by commit
07fa917a33 ("arm64: dts: qcom: sm8450: add ufs nodes") but the binding
was never updated to match.

Fixes: e04121ba1b ("dt-bindings: phy: qcom,qmp: Add SM8450 UFS phy compatible")
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20220830112923.3725-17-johan+linaro@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/qcom,qmp-ufs-phy.yaml

@@ -42,11 +42,11 @@ properties:
 
   clocks:
     minItems: 1
-    maxItems: 2
+    maxItems: 3
 
   clock-names:
     minItems: 1
-    maxItems: 2
+    maxItems: 3
 
   resets:
     maxItems: 1
@@ -117,6 +117,22 @@ allOf:
             - const: ref
             - const: ref_aux
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - qcom,sm8450-qmp-ufs-phy
+    then:
+      properties:
+        clocks:
+          maxItems: 3
+        clock-names:
+          items:
+            - const: ref
+            - const: ref_aux
+            - const: qref
+
 examples:
   - |
     #include <dt-bindings/clock/qcom,gcc-sc8280xp.h>