board: rockchip: add Khadas Edge2 RK3588 board

board: rockchip: add Khadas Edge2 RK3588 board

Khadas Edge2 is a Rockchip RK3588S based SBC (Single Board Computer)
by Khadas.

There are tree variants depending on the DRAM size : 8G and 16G.

Specification:

    Rockchip RK3588S SoC
    4x ARM Cortex-A76, 4x ARM Cortex-A55
    8/16GB memory LPDDR4x
    Mali G610MP4 GPU
    3x MIPI CSI 4x lanes
    2x MIPI-DSI DPHY 4x lanes
    32/64GB eMMC
    1x USB 2.0, 1x USB 3.0, 2x USB-Type-C
    1x HDMI 2.1 output, 1x DP 1.4 output
    USB PD over USB Type-C

Kernel commit:
04d552993522 ("arm64: dts: rockchip: Add Khadas edge2 board")

Signed-off-by: Jacobe Zang <jacobe.zang@wesion.com>