dt-bindings: add vendor prefix for Lichee Pi

Lichee Pi is a new "Pi"-named development board series.

Currently available device, Lichee Pi One, is by only one person as
night job, so the device series name is chosen to be the vendor prefix.
Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -161,6 +161,7 @@ lacie	LaCie
 lantiq	Lantiq Semiconductor
 lenovo	Lenovo Group Ltd.
 lg	LG Corporation
+licheepi	Lichee Pi
 linux	Linux-specific binding
 lltc	Linear Technology Corporation
 lsi	LSI Corp. (LSI Logic)