Both of type of watchdogs described in the binding (the KPSS watchdog
and APSS WDT timer) have interrupts.  Allow interrupts and describe them
for KPSS watchdog to fix warnings like:

  watchdog@17c10000: Unevaluated properties are not allowed ('interrupts' was unexpected)
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20221212163532.142533-5-krzysztof.kozlowski@linaro.orgSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>