watchdog: meson: keep running if already active

If the watchdog is already running (e.g.: started by bootloader) then
the kernel driver should keep the watchdog active but the amlogic driver
turns it off.

Let the driver fix the clock rate if already active because we do not
know the previous timebase value. To avoid unintentional resetting we
temporarily set it to its maximum value.

Then keep the enable bit if is was previously active.

Signed-off-by: Philippe Boos <pboos@baylibre.com>
Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220801092150.4449-1-pboos@baylibre.com


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