riscv: dts: sophgo: rename header file cv18xx.dtsi to cv180x.dtsi

riscv: dts: sophgo: rename header file cv18xx.dtsi to cv180x.dtsi

As the cv18xx.dtsi serves as a common peripheral header for all
riscv cv180x/cv181x/sg200x SoCs, it not cover the entire cv18xx
series as there is cv182x and cv183x. So rename the header file
to make it precise.

Reviewed-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Link: https://lore.kernel.org/r/20250430012654.235830-4-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>