riscv: dts: sophgo: enable hardware clock (RTC) on the Milk-V Pioneer

riscv: dts: sophgo: enable hardware clock (RTC) on the Milk-V Pioneer

These boards have a working hardware clock if you put a CR-1220
battery in them. We enable it using information from a 6.1.x vendor
kernel.

Reviewed-by: Chen Wang <unicorn_wang@outlook.com>
Signed-off-by: Michael Orlitzky <michael@orlitzky.com>
Link: https://lore.kernel.org/r/20260107112922.20013-2-michael@orlitzky.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>