dt-bindings: watchdog: fsl-imx: document suspend in wait mode

Property "fsl,suspend-in-wait" suspends watchdog in "WAIT" mode which
corresponds to Linux's Suspend-to-Idle S0 mode. If this property is not
set and the device is put into Suspend-to-Idle mode, the watchdog
triggers a reset after 128 seconds.

Signed-off-by: Andrej Picej <andrej.picej@norik.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20221104070358.426657-3-andrej.picej@norik.com


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