ARM: rockchip: disable watchdog during suspend

The watchdog clock should be disable in dw_wdt_suspend, but we set a
dummy clock to watchdog for rk3288. So the watchdog will continue to
work during suspend. And we switch the system clock to 32khz from 24Mhz,
during suspend, so the watchdog timer over count will increase to
755 times, about 12.5 hours, the original value is 60 seconds. So
watchdog will reset the system over a night,  but voltage are all
incorrect, then it hang on reset.

Signed-off-by: Chris Zhong <zyw@rock-chips.com>
Signed-off-by: Daniel Kurtz <djkurtz@google.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Tested-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>