board: rockchip: Add FriendlyElec NanoPi R6S

The NanoPi R6S is a SBC by FriendlyElec based on the Rockchip RK3588s.
It comes with 4GB or 8GB of RAM, a microSD card slot, 32GB eMMC storage,
one RTL8211F 1GbE and two RTL8125 2.5GbE Ethernet ports, one USB 2.0
Type-A and one USB 3.0 Type-A port, a HDMI port, a 12-pin GPIO FPC
connector, a fan connector, IR receiver as well as some buttons and LEDs.

Add initial support for this board using the upstream devicetree sources.

Kernel commit:
f1b11f43b3e9 ("arm64: dts: rockchip: Add support for NanoPi R6S")

Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Sebastian Kropatsch <seb-dev@mail.de>
diff --git a/configs/nanopi-r6s-rk3588s_defconfig b/configs/nanopi-r6s-rk3588s_defconfig
new file mode 100644
index 0000000..f7b3646
--- /dev/null
+++ b/configs/nanopi-r6s-rk3588s_defconfig
@@ -0,0 +1,82 @@
+CONFIG_ARM=y
+CONFIG_SKIP_LOWLEVEL_INIT=y
+CONFIG_SYS_HAS_NONCACHED_MEMORY=y
+CONFIG_COUNTER_FREQUENCY=24000000
+CONFIG_ARCH_ROCKCHIP=y
+CONFIG_DEFAULT_DEVICE_TREE="rockchip/rk3588s-nanopi-r6s"
+CONFIG_ROCKCHIP_RK3588=y
+CONFIG_SPL_SERIAL=y
+CONFIG_TARGET_NANOPI_R6S_RK3588S=y
+CONFIG_DEBUG_UART_BASE=0xFEB50000
+CONFIG_DEBUG_UART_CLOCK=24000000
+CONFIG_SYS_LOAD_ADDR=0xc00800
+CONFIG_PCI=y
+CONFIG_DEBUG_UART=y
+CONFIG_FIT=y
+CONFIG_FIT_VERBOSE=y
+CONFIG_SPL_FIT_SIGNATURE=y
+CONFIG_SPL_LOAD_FIT=y
+CONFIG_LEGACY_IMAGE_FORMAT=y
+CONFIG_DEFAULT_FDT_FILE="rockchip/rk3588s-nanopi-r6s.dtb"
+# CONFIG_DISPLAY_CPUINFO is not set
+CONFIG_DISPLAY_BOARDINFO_LATE=y
+CONFIG_SPL_MAX_SIZE=0x40000
+CONFIG_SPL_PAD_TO=0x7f8000
+# CONFIG_SPL_RAW_IMAGE_SUPPORT is not set
+CONFIG_SPL_ATF=y
+CONFIG_CMD_GPIO=y
+CONFIG_CMD_PWM=y
+CONFIG_CMD_GPT=y
+CONFIG_CMD_I2C=y
+CONFIG_CMD_MMC=y
+CONFIG_CMD_PCI=y
+CONFIG_CMD_USB=y
+CONFIG_CMD_ROCKUSB=y
+# CONFIG_CMD_SETEXPR is not set
+CONFIG_CMD_REGULATOR=y
+# CONFIG_SPL_DOS_PARTITION is not set
+CONFIG_SPL_OF_CONTROL=y
+CONFIG_OF_LIVE=y
+CONFIG_OF_SPL_REMOVE_PROPS="clock-names interrupt-parent assigned-clocks assigned-clock-rates assigned-clock-parents"
+CONFIG_SPL_DM_SEQ_ALIAS=y
+CONFIG_SPL_REGMAP=y
+CONFIG_SPL_SYSCON=y
+CONFIG_SPL_CLK=y
+# CONFIG_USB_FUNCTION_FASTBOOT is not set
+CONFIG_ROCKCHIP_GPIO=y
+CONFIG_SYS_I2C_ROCKCHIP=y
+CONFIG_MISC=y
+CONFIG_SUPPORT_EMMC_RPMB=y
+CONFIG_MMC_DW=y
+CONFIG_MMC_DW_ROCKCHIP=y
+CONFIG_MMC_SDHCI=y
+CONFIG_MMC_SDHCI_SDMA=y
+CONFIG_MMC_SDHCI_ROCKCHIP=y
+# CONFIG_SPI_FLASH is not set
+CONFIG_PHY_REALTEK=y
+CONFIG_DWC_ETH_QOS=y
+CONFIG_DWC_ETH_QOS_ROCKCHIP=y
+CONFIG_RTL8169=y
+CONFIG_PCIE_DW_ROCKCHIP=y
+CONFIG_PHY_ROCKCHIP_INNO_USB2=y
+CONFIG_PHY_ROCKCHIP_NANENG_COMBOPHY=y
+CONFIG_PHY_ROCKCHIP_USBDP=y
+CONFIG_SPL_PINCTRL=y
+CONFIG_PWM_ROCKCHIP=y
+CONFIG_SPL_RAM=y
+CONFIG_BAUDRATE=1500000
+CONFIG_DEBUG_UART_SHIFT=2
+CONFIG_SYS_NS16550_MEM32=y
+CONFIG_SYSRESET=y
+CONFIG_USB=y
+CONFIG_USB_XHCI_HCD=y
+CONFIG_USB_EHCI_HCD=y
+CONFIG_USB_EHCI_GENERIC=y
+CONFIG_USB_OHCI_HCD=y
+CONFIG_USB_OHCI_GENERIC=y
+CONFIG_USB_DWC3=y
+CONFIG_USB_DWC3_GENERIC=y
+CONFIG_USB_GADGET=y
+CONFIG_USB_GADGET_DOWNLOAD=y
+CONFIG_USB_FUNCTION_ROCKUSB=y
+CONFIG_ERRNO_STR=y