arm64: dts: rockchip: Add FriendlyElec NanoPi M5 support

arm64: dts: rockchip: Add FriendlyElec NanoPi M5 support

Add device tree for FriendlyElec NanoPi M5 with Rockchip RK3576 SoC
(4x Cortex-A72, 4x Cortex-A53, Mali-G52 MC3 GPU, 6 TOPS NPU). Enables
basic booting and connectivity.

Supported features:
- RK3576 SoC
- 4GB LPDDR4X or 8GB/16GB LPDDR5
- 16MB SPI Nor Flash
- 2x 1Gbps Ethernet
- 2x USB 3.2 Gen 1 Type-A ports
- M.2 M-Key PCIe 2.1 x1 NVMe support
- M.2 E-Key SDIO connector
- microSD UHS-I
- HDMI 1.4/2.0 (up to 4096x2304@60Hz)
- 30-pin GPIO (2x SPI, 4x UART, 3x I2C, 5x PWM, 20x GPIO)
- Debug UART
- RTC with HYM8563TS
- Power via USB-C (PD, 6V~20V)

Signed-off-by: John Clark <inindev@gmail.com>
Link: https://lore.kernel.org/r/20250628143229.74460-3-inindev@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>