dt-bindings: Add vendor prefix for Xiaomi

Xiaomi Corporation is a Chinese electronics company.
Signed-off-by: Alexey Minnekhanov <alexey.min@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.yaml

@@ -1086,6 +1086,8 @@ patternProperties:
     description: X-Powers
   "^xes,.*":
     description: Extreme Engineering Solutions (X-ES)
+  "^xiaomi,.*":
+    description: Xiaomi Technology Co., Ltd.
   "^xillybus,.*":
     description: Xillybus Ltd.
   "^xinpeng,.*":