dt-bindings: Add "mrvl", a legacy vendor prefix for Marvell

While the preferred vendor prefix is "marvell", "mrvl" is used by many
older bindings already. Add it, while also marking it deprecated.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.yaml

@@ -639,6 +639,9 @@ patternProperties:
     description: Monolithic Power Systems Inc.
   "^mqmaker,.*":
     description: mqmaker Inc.
+  "^mrvl,.*":
+    description: Marvell Technology Group Ltd.
+    deprecated: true
   "^mscc,.*":
     description: Microsemi Corporation
   "^msi,.*":