riscv: dts: spacemit: add initial support for K3 SoC

SpacemiT K3 is equipped with 8 X100 cores, which are RVA23 compliant.
Add nodes of uarts, timer and interrupt-controllers. Also add M-mode
APLIC (maplic) and IMSIC (mimsic) nodes to represent the hardware
topology and ready for potential firmware usage.

Signed-off-by: Guodong Xu <guodong@riscstar.com>
Link: https://lore.kernel.org/r/20260115-k3-basic-dt-v5-6-6990ac9f4308@riscstar.com
Signed-off-by: Yixun Lan <dlan@kernel.org>

Author: docularxu