riscv: dts: add initial SpacemiT K1 SoC device tree

Banana Pi BPI-F3 motherboard is powered by SpacemiT K1[1].

Key features:
- 4 cores per cluster, 2 clusters on chip
- UART IP is Intel XScale UART

Some key considerations:
- ISA string is inferred from vendor documentation[2]
- Cluster topology is inferred from datasheet[1] and L2 in vendor dts[3]
- No coherent DMA on this board
    Inferred by taking vendor ethernet and MMC drivers to the mainline
    kernel. Without dma-noncoherent in soc node, the driver fails.
- Add cache nodes
    K1 SoC has 128 sets of 32KiB L1 I/D Cache for each hart, and 512 sets
    of 512KiB L2 Cache for each cluster.

Currently only support booting into console with only uart, other
features will be added soon later.

Link: https://docs.banana-pi.org/en/BPI-F3/SpacemiT_K1_datasheet [1]
Link: https://developer.spacemit.com/#/documentation?token=BWbGwbx7liGW21kq9lucSA6Vnpb [2]
Link: https://gitee.com/bianbu-linux/linux-6.1/blob/bl-v1.0.y/arch/riscv/boot/dts/spacemit/k1-x.dtsi [3]
Signed-off-by: Yangyu Chen <[email protected]>
Acked-by: Jesse Taube <[email protected]>
Acked-by: Palmer Dabbelt <[email protected]>
Signed-off-by: Yixun Lan <[email protected]>

Author: cyyself