riscv: dts: canaan: Add basic device tree for K230 CanMV board

riscv: dts: canaan: Add basic device tree for K230 CanMV board

Add initial dts for K230-CanMV powered by Canaan Kendryte K230 SoC,
which has two RISC-V C908 cores, a big core with vector 1.0 extension
and a small core without vector extension.

This patch is basically comes from Linux Kernel [1] and it assumes
u-boot is running on the big core. Additionally, bootctl and reboot nodes
are added to support sysreset [2] and an clk_dummy node is added to
satisfy dependencies for usb [3].

Currently, u-boot is booted by the vendor's u-boot-spl. To meet the
requirements [4][5] of vendor's u-boot-spl for u-boot, a binman node with
mkimage child node is added here, which will compress u-boot.bin with
gzip and generate an image named "uboot" in the file u-boot-gz.img.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git/log/?h=k230-basic
[2] https://github.com/kendryte/k230_sdk/blob/v1.8/src/big/rt-smart/kernel/bsp/maix3/board/interdrv/sysctl/sysctl_boot/sysctl_boot.c#L67
[3] https://lore.kernel.org/linux-riscv/tencent_AD84B436C2F31108B66B4739D6E306C5E80A@qq.com/
[4] https://github.com/kendryte/k230_sdk/blob/v1.8/src/little/uboot/board/canaan/common/k230_img.c#L306
[5] https://github.com/kendryte/k230_sdk/blob/v1.8/src/little/uboot/board/canaan/common/k230_img.c#L125

Signed-off-by: Junhui Liu <junhui.liu@pigmoral.tech>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>