configs: andes: add watchdog support fot andes ae350

It adds the ATCWDT200 support for Andes AE350 platform.
It also enables wdt command support.

Signed-off-by: CL Wang <cl634@andestech.com>
Signed-off-by: Randolph <randolph@andestech.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>