Lichee zero plus is a core board made by Sipeed, which includes on-board
TF slot or SMT SD NAND, and optional SPI NOR or eMMC, a UART debug
header, a microUSB slot and a gold finger connector for expansion. It
can use either Sochip S3 or Allwinner S3L SoC.

Add the basic device tree for the core board, w/o optional onboard
storage, and with S3 SoC.
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>