dt-bindings: mtd: fixed-partitions: Move "compression" to partition node

The "compression" property is defined in the wrong place as it applies
to individual partitions nodes, not all nodes.

Fixes: 8baba8d52f ("dt-bindings: mtd: fixed-partitions: Add compression property")
Reviewed-by: Simon Glass <simon.glass@canonical.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Documentation/devicetree/bindings/mtd/partitions/partition.yaml

@@ -108,6 +108,24 @@ properties:
       with the padding bytes, so may grow. If ‘align-end’ is not provided,
       no alignment is performed.
 
+  compression:
+    $ref: /schemas/types.yaml#/definitions/string
+    description: |
+      Compression algorithm used to store the data in this partition, chosen
+      from a list of well-known algorithms.
+
+      The contents are compressed using this algorithm.
+
+    enum:
+      - none
+      - bzip2
+      - gzip
+      - lzop
+      - lz4
+      - lzma
+      - xz
+      - zstd
+
 if:
   not:
     required: [ reg ]