dt-bindings: i2c: realtek,rtl9301: Fix missing 'reg' constraint

Lists should have fixed amount if items, so add missing constraint to
the 'reg' property (only one address space entry).

Fixes: c5eda03 ("dt-bindings: i2c: Add Realtek RTL I2C Controller")
Cc: <[email protected]> # v6.13+
Signed-off-by: Krzysztof Kozlowski <[email protected]>
Signed-off-by: Andi Shyti <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: krzk

Documentation/devicetree/bindings/i2c/realtek,rtl9301-i2c.yaml

@@ -26,7 +26,8 @@ properties:
       - const: realtek,rtl9301-i2c
 
   reg:
-    description: Register offset and size this I2C controller.
+    items:
+      - description: Register offset and size this I2C controller.
 
   "#address-cells":
     const: 1