watchdog: Convert wm831x driver to watchdog core

Fairly large code churn but not much doing with that and the overall
result is a definite win.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/Kconfig

@@ -66,6 +66,7 @@ config SOFT_WATCHDOG
 config WM831X_WATCHDOG
 	tristate "WM831x watchdog"
 	depends on MFD_WM831X
+	select WATCHDOG_CORE
 	help
 	  Support for the watchdog in the WM831x AudioPlus PMICs.  When
 	  the watchdog triggers the system will be reset.