dt-bindings: i2c: opencores: Add missing type for "regstep"

"regstep" may be deprecated, but it still needs a type.

Fixes: 8ad69f4 ("dt-bindings: i2c: convert ocores binding to yaml")
Signed-off-by: Rob Herring <[email protected]>
Reviewed-by: Andrew Lunn <[email protected]>
Reviewed-by: Peter Korsgaard <[email protected]>
Reviewed-by: Conor Dooley <[email protected]>
Acked-by: Andi Shyti <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>

Author: robherring

Documentation/devicetree/bindings/i2c/opencores,i2c-ocores.yaml

@@ -60,6 +60,7 @@ properties:
     default: 0
 
   regstep:
+    $ref: /schemas/types.yaml#/definitions/uint32
     description: |
       deprecated, use reg-shift above
     deprecated: true