dt-bindings: mtd: spi-nor: add otp property

SPI-NOR flashes may have OTP regions and have a nvmem binding. This
binding is described in mtd.yaml.
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210424110608.15748-5-michael@walle.cc

Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml

@@ -9,6 +9,9 @@ title: SPI NOR flash ST M25Pxx (and similar) serial flash chips
 maintainers:
   - Rob Herring <robh@kernel.org>
 
+allOf:
+  - $ref: "mtd.yaml#"
+
 properties:
   compatible:
     oneOf:
@@ -82,6 +85,9 @@ patternProperties:
   '^partition@':
     type: object
 
+  "^otp(-[0-9]+)?$":
+    type: object
+
 additionalProperties: false
 
 examples: