watchdog: atcwdt200: Add driver for Andes ATCWDT200

watchdog: atcwdt200: Add driver for Andes ATCWDT200

Add support for the Andes ATCWDT200 watchdog timer. The driver implements
programmable reset and interrupt timers, and includes automatic detection
of the supported IntTime bit-width.

Integrated with the Linux watchdog framework, it supports basic operations
including start, stop, ping, timeout configuration, and system reset via
the restart handler.

Signed-off-by: CL Wang <cl634@andestech.com>
Link: https://lore.kernel.org/r/20260115081444.2452357-3-cl634@andestech.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>