riscv: dts: sophgo: Move PLIC and CLINT node into CPU dtsi

riscv: dts: sophgo: Move PLIC and CLINT node into CPU dtsi

As we have a separate CPU dtsi file, move the PLIC and CLINT
node to the CPU dtsi file. This will make the sg2042.dtsi focus
on peripheral devices, and make the CPU dtsi force CPU related
devices.

Reviewed-by: Chen Wang <unicorn_wang@outlook.com>
Link: https://lore.kernel.org/r/20260113023828.790136-1-inochiama@gmail.com
Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
Signed-off-by: Chen Wang <wangchen20@iscas.ac.cn>