dt-bindings: phy: samsung,ufs-phy: make pmu-syscon as phandle-array

To support secondary ufs phy devices, we need to get an offset value
from pmu-syscon.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Link: https://lore.kernel.org/r/20220607072907.127000-2-chanho61.park@samsung.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/samsung,ufs-phy.yaml

@@ -40,9 +40,17 @@ properties:
       - const: tx0_symbol_clk
 
   samsung,pmu-syscon:
-    $ref: '/schemas/types.yaml#/definitions/phandle'
-    description: phandle for PMU system controller interface, used to
-                 control pmu registers bits for ufs m-phy
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    maxItems: 1
+    items:
+      minItems: 1
+      items:
+        - description: phandle for PMU system controller interface, used to
+                       control pmu registers bits for ufs m-phy
+        - description: offset of the pmu control register
+    description:
+      It can be phandle/offset pair. The second cell which can represent an
+      offset is optional.
 
 required:
   - "#phy-cells"