dt-bindings: Add vendor prefix for SG Micro Corp

"SG Micro Corp (SGMICRO) specializes in high performance, high quality
analog IC design, marketing and sales." (http://www.sg-micro.com/)
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.yaml

@@ -869,6 +869,8 @@ patternProperties:
     description: Small Form Factor Committee
   "^sgd,.*":
     description: Solomon Goldentek Display Corporation
+  "^sgmicro,.*":
+    description: SG Micro Corp
   "^sgx,.*":
     description: SGX Sensortech
   "^sharp,.*":