watchdog: Exar/MaxLinear XR28V38x driver

Simple driver for the watchdog present in some Exar/MaxLinear UART chips.
Please see https://www.maxlinear.com/product/interface/uarts/lpc-uarts/xr28v384


for more info.

Signed-off-by: David Müller <d.mueller@elsoft.ch>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220914094605.93377-1-d.mueller@elsoft.ch


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