board: rockchip: Add FriendlyElec NanoPi R6C

The NanoPi R6C is a SBC by FriendlyElec based on the Rockchip RK3588s.
It comes with 4GB or 8GB of RAM, a microSD card slot, optional 32GB eMMC
storage, one M.2 M-Key connector, one RTL8211F 1GbE and one RTL8125
2.5GbE Ethernet port, one USB 2.0 Type-A and one USB 3.0 Type-A port, a
HDMI port, a 30-pin GPIO header as well as multiple buttons and LEDs.

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

Tested in U-Boot proper:
- Booting from eMMC works
- 1GbE Ethernet works using the eth_eqos driver (tested by ping)
- 2.5GbE Ethernet works using the eth_rtl8169 driver (tested by ping),
  but the status LEDs on this specific port currently aren't working
- NVMe SSD in M.2 socket does get recognized (tested with `nvme scan`
  followed by `nvme details`)

Kernel commit:
d5f1d7437451 ("arm64: dts: rockchip: Add support for NanoPi R6C")

Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Sebastian Kropatsch <seb-dev@mail.de>
diff --git a/arch/arm/mach-rockchip/rk3588/Kconfig b/arch/arm/mach-rockchip/rk3588/Kconfig
index 9a35c7d..26e45f4 100644
--- a/arch/arm/mach-rockchip/rk3588/Kconfig
+++ b/arch/arm/mach-rockchip/rk3588/Kconfig
@@ -78,6 +78,18 @@
 	  Power: 5.5*2.1mm DC Jack, 12VDC input
 	  Dimensions: 110x80x1.6mm (without case) / 86x114.5x30mm (with case)
 
+config TARGET_NANOPI_R6C_RK3588S
+	bool "FriendlyElec NanoPi R6C"
+	select BOARD_LATE_INIT
+	help
+	  The NanoPi R6C is a SBC by FriendlyElec based on the Rockchip
+	  RK3588s.
+	  It comes with 4GB or 8GB of RAM, a microSD card slot, optional 32GB
+	  eMMC storage, one M.2 M-Key connector, one RTL8211F 1GbE and one
+	  RTL8125 2.5GbE Ethernet port, one USB 2.0 Type-A and one USB 3.0
+	  Type-A port, a HDMI port, a 30-pin GPIO header as well as some
+	  buttons and LEDs.
+
 config TARGET_NOVA_RK3588
 	bool "Indiedroid Nova RK3588"
 	select BOARD_LATE_INIT
@@ -288,6 +300,7 @@
 source "board/armsom/sige7-rk3588/Kconfig"
 source "board/edgeble/neural-compute-module-6/Kconfig"
 source "board/friendlyelec/nanopc-t6-rk3588/Kconfig"
+source "board/friendlyelec/nanopi-r6c-rk3588s/Kconfig"
 source "board/indiedroid/nova/Kconfig"
 source "board/pine64/quartzpro64-rk3588/Kconfig"
 source "board/turing/turing-rk1-rk3588/Kconfig"