Lichee Pi One is a low-cost Allwinner A13-based development board, with
an AXP209 PMU, a USB2.0 OTG port, a USB2.0 host port (or an onboard
RTL8723BU Wi-Fi card), optional headers for LCD and CSI, two GPIO
headers and two MicroSD card slots (connected to mmc0 and mmc2, both
bootable).

Add support for it.

Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>