dt-bindings: vendor-prefixes: Add "test" vendor for KUnit and friends

Add the vendor prefix "test" to reserve a vendor prefix for bindings
that are purely for testing device tree code. This allows test code to
write bindings that can be checked by the schema validator.

Reviewed-by: Rob Herring <[email protected]>
Reviewed-by: David Gow <[email protected]>
Cc: Krzysztof Kozlowski <[email protected]>
Cc: Conor Dooley <[email protected]>
Signed-off-by: Stephen Boyd <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: bebarino

Documentation/devicetree/bindings/vendor-prefixes.yaml

@@ -1476,6 +1476,8 @@ patternProperties:
     description: Terasic Inc.
   "^tesla,.*":
     description: Tesla, Inc.
+  "^test,.*":
+    description: Reserved for use by tests. For example, KUnit.
   "^tfc,.*":
     description: Three Five Corp
   "^thead,.*":