dt-bindings: mtd-physmap: Add 'arm,vexpress-flash' compatible

The 'arm,vexpress-flash' compatible is in use, but has never been documented,
so add it now.

Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: linux-mtd@lists.infradead.org
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20210819182427.1175753-1-robh@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/mtd/mtd-physmap.yaml

@@ -23,6 +23,7 @@ properties:
               - amd,s29gl256n
               - amd,s29gl512n
               - arm,versatile-flash
+              - arm,vexpress-flash
               - cortina,gemini-flash
               - cypress,hyperflash
               - ge,imp3a-firmware-mirror