dt-bindings: Add vendor prefix for arcx / Archronix

dt-bindings: Add vendor prefix for arcx / Archronix

arcx Inc. is an engineering company which provides advanced
embedded systems and consulting services.

Archronix is a technology design and product engineering firm
specializing in hardware control systems and enabling software.
Clients include OEM's in the transportation, aerospace,
medical and commercial sectors.

Websites:
	http://www.arcx.com/
	http://www.archronix.com/

Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>