documentation: devicetree: Added xillybus to vendor-prefixes

Signed-off-by: NEli Billauer <eli.billauer@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -147,6 +147,7 @@ winbond Winbond Electronics corp.
 wlf	Wolfson Microelectronics
 wm	Wondermedia Technologies, Inc.
 xes	Extreme Engineering Solutions (X-ES)
+xillybus	Xillybus Ltd.
 xlnx	Xilinx
 zyxel	ZyXEL Communications Corp.
 zarlink	Zarlink Semiconductor