sun50i: h5: Add initial Orange Pi Zero Plus support

Orange Pi Zero Plus is an open-source single-board computer
using the Allwinner H5 SOC.

H5 Orangepi Zero Plus has
 - Quad-core Cortex-A53
 - 512MB DDR3
 - micrSD slot
 - 16MBit SPI Nor flash
 - Debug TTL UART
 - 1GBit/s Ethernet (RTL8211E)
 - Wifi (RTL8189FTV)
 - USB 2.0 Host
 - USB 2.0 OTG + power supply

The device tree file is copied from the Linux kernel 4.17.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>