mfd: da9062: Fix watchdog compatible string

The watchdog driver compatible is "dlg,da9062-watchdog" and not
"dlg,da9062-wdt". Therefore the mfd-core can't populate the of_node and
fwnode. As result the watchdog driver can't parse the devicetree.

Fixes: 9b40b030 ("mfd: da9062: Supply core driver")
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>