watchdog: qcom-wdt: Do not set 'dev' in struct watchdog_device

The 'dev' pointer in struct watchdog_device is set by the watchdog core
when registering the watchdog device and not by the driver. It points to
the watchdog device, not its parent.

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