dt-bindings: fix vendor prefix for Abracon

Commit 446810f ("of: add vendor prefix for Abracon Corporation")
claimed that "abcn" was used as the vendor prefix while in fact "abracon"
was used in the subsequent commits. It is also the only prefix used in the
tree.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
[robh: fix alphabetical order]
Signed-off-by: Rob Herring <robh@kernel.org>

Author: alexandrebelloni

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -3,8 +3,8 @@ Device tree binding vendor prefix registry.  Keep list in alphabetical order.
 This isn't an exhaustive list, but you should add new prefixes to it before
 using them to avoid name-space collisions.
 
-abcn	Abracon Corporation
 abilis	Abilis Systems
+abracon	Abracon Corporation
 actions	Actions Semiconductor Co., Ltd.
 active-semi	Active-Semi International Inc
 ad	Avionic Design GmbH