drivers: watchdog: Add StarFive Watchdog driver

Add watchdog driver for the StarFive JH7100 and JH7110 SoC.

Signed-off-by: Xingyu Wu <xingyu.wu@starfivetech.com>
Reviewed-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230314132437.121534-3-xingyu.wu@starfivetech.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>