dt-bindings: mtd: sunxi: Add new compatible

The A23/A33 NAND controller is slightly different than the A10+ ones,
eg. DMA handling is a bit different and a few register offsets
changed.

Introduce a new compatible to represent this version of the IP.

Also append '-controller' to the new compatible (which is required for
new compatibles) as this is describing a NAND controller and not a
NAND chip.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Documentation/devicetree/bindings/mtd/allwinner,sun4i-a10-nand.yaml

@@ -18,8 +18,9 @@ properties:
   "#size-cells": true
 
   compatible:
-    const: allwinner,sun4i-a10-nand
-
+    enum:
+      - allwinner,sun4i-a10-nand
+      - allwinner,sun8i-a23-nand-controller
   reg:
     maxItems: 1