arm64: dts: rockchip: add MNT Reform 2 laptop

arm64: dts: rockchip: add MNT Reform 2 laptop

MNT Reform 2 is an open source laptop with replaceable CPU modules,
including a version with the RK3588-based MNT RCORE[1], which is based
on Firefly's iCore-3588Q SoM:

- Rockchip RK3588
- Quad A76 and Quad A55 CPU
- 6 TOPS NPU
- up to 32GB LPDDR4x RAM
- SD Card slot
- Gigabit ethernet port
- HDMI port
- 2x mPCIe ports for WiFi or NVMe
- 3x USB 3.0 Type-A HOST port

[1] https://shop.mntre.com/products/mnt-reform

Co-developed-by: "Lukas F. Hartmann" <lukas@mntre.com>
Signed-off-by: "Lukas F. Hartmann" <lukas@mntre.com>
Signed-off-by: Patrick Wildt <patrick@blueri.se>
Link: https://lore.kernel.org/r/Z8S6uDM634KJuyKP@windev.fritz.box
Signed-off-by: Heiko Stuebner <heiko@sntech.de>