dt-bindings: mtd: Add SEAMA partition bindings

This types of NAND partitions appear in OpenWrt and
U-Boot.

Signed-off-by: Linus Walleij <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Miquel Raynal <[e-mail]>
Link: https://lore.kernel.org/linux-mtd/[e-mail]

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

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mtd/partitions/seama.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Seattle Image Partitions
+
+description: The SEAttle iMAge (SEAMA) partition is a type of partition
+  used for NAND flash devices. This type of flash image is found in some
+  D-Link routers such as DIR-645, DIR-842, DIR-859, DIR-860L, DIR-885L,
+  DIR890L and DCH-M225, as well as in WD and NEC routers on the ath79
+  (MIPS), Broadcom BCM53xx, and RAMIPS platforms. This partition type
+  does not have children defined in the device tree, they need to be
+  detected by software.
+
+allOf:
+  - $ref: partition.yaml#
+
+maintainers:
+  - Linus Walleij <[e-mail]>
+
+properties:
+  compatible:
+    const: seama
+
+required:
+  - compatible
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    partitions {
+        compatible = "fixed-partitions";
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        partition@0 {
+            compatible = "seama";
+            reg = <0x0 0x800000>;
+            label = "firmware";
+        };
+    };