The wd command already warns that "Watchdog cannot be disabled",
when the stop operation returns -ENOSYS. We do that now, so telling the
user that it will not stop is superfluous. Remove it.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>