riscv: dts: spacemit: add MusePi Pro board device tree

riscv: dts: spacemit: add MusePi Pro board device tree

Add initial device tree support for the MusePi Pro board [1].
The board is using the SpacemiT K1/M1 SoC.

This device tree is adapted from the SpacemiT vendor tree [2] and
enables basic board functionality, including UART console, LED, eMMC,
Ethernet, and PDMA.

Link: https://developer.spacemit.com/documentation?token=YJtdwnvvViPVcmkoPDpcvwfVnrh&type=pdf
Link: https://gitee.com/bianbu-linux/linux-6.6/blob/k1-bl-v2.2.y/arch/riscv/boot/dts/spacemit/k1-x_MUSE-Pi-Pro.dts
Signed-off-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Link: https://lore.kernel.org/r/20251023-k1-musepi-pro-dts-v4-2-01836303e10f@linux.spacemit.com
Signed-off-by: Yixun Lan <dlan@gentoo.org>