dt-bindings: Add vendor prefix for TechNexion

TechNexion designs and manufactures embedded computing systems:
http://www.technexion.com/Signed-off-by: NFabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: NRob Herring <robh@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -255,6 +255,7 @@ synology	Synology, Inc.
 SUNW	Sun Microsystems, Inc
 tbs	TBS Technologies
 tcl	Toby Churchill Ltd.
+technexion	TechNexion
 technologic	Technologic Systems
 thine	THine Electronics, Inc.
 ti	Texas Instruments