dt-bindings: mtd: refactor NAND bindings and add nand-controller-legacy.yaml

The modern NAND controller binding requires NAND chips to be described as
child nodes of the controller, for example:

  nand-controller {
          ...
          nand@0 {
                  /* raw NAND chip properties */
          };
  };

However, many existing device trees place NAND chip properties directly
within the controller node because those controllers support only a single
chip. This layout is still widely used by older platforms and by other DT
consumers such as U-Boot. Migrating all existing users to the new layout
will take time.

Several kernel drivers, such as ams-delta.c, davinci_nand.c and
fsmc_nand.c, still expect the legacy layout where raw NAND properties are
defined in the controller node.

To support both layouts during the transition:

- Extract NAND chip-related properties into separate schemas
  (nand-property.yaml and raw-nand-property.yaml) from
  nand-chip.yaml and raw-nand-chip.yaml.
- Introduce nand-controller-legacy.yaml to allow both the
  legacy and modern layouts.
- Add a select condition in nand-controller.yaml to prevent
  node name pattern matching for fsl,* NAND controllers.

Keep compatibility with existing device trees while allowing gradual
migration to the modern binding structure.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Documentation/devicetree/bindings/mtd/nand-chip.yaml

@@ -11,6 +11,7 @@ maintainers:
 
 allOf:
   - $ref: mtd.yaml#
+  - $ref: nand-property.yaml
 
 description: |
   This file covers the generic description of a NAND chip. It implies that the
@@ -22,51 +23,6 @@ properties:
     description:
       Contains the chip-select IDs.
 
-  nand-ecc-engine:
-    description: |
-      A phandle on the hardware ECC engine if any. There are
-      basically three possibilities:
-      1/ The ECC engine is part of the NAND controller, in this
-      case the phandle should reference the parent node.
-      2/ The ECC engine is part of the NAND part (on-die), in this
-      case the phandle should reference the node itself.
-      3/ The ECC engine is external, in this case the phandle should
-      reference the specific ECC engine node.
-    $ref: /schemas/types.yaml#/definitions/phandle
-
-  nand-use-soft-ecc-engine:
-    description: Use a software ECC engine.
-    type: boolean
-
-  nand-no-ecc-engine:
-    description: Do not use any ECC correction.
-    type: boolean
-
-  nand-ecc-algo:
-    description:
-      Desired ECC algorithm.
-    $ref: /schemas/types.yaml#/definitions/string
-    enum: [hamming, bch, rs]
-
-  nand-ecc-strength:
-    description:
-      Maximum number of bits that can be corrected per ECC step.
-    $ref: /schemas/types.yaml#/definitions/uint32
-    minimum: 1
-
-  nand-ecc-step-size:
-    description:
-      Number of data bytes covered by a single ECC step.
-    $ref: /schemas/types.yaml#/definitions/uint32
-    minimum: 1
-
-  secure-regions:
-    description:
-      Regions in the NAND chip which are protected using a secure element
-      like Trustzone. This property contains the start address and size of
-      the secure regions present.
-    $ref: /schemas/types.yaml#/definitions/uint64-matrix
-
 required:
   - reg