watchdog: fix set_timeout operations

Since we changed the behaviour of the set_timeout operation in the
watchdog API, we need to change the allready converted drivers so
that they update the timeout field at the end of the set_timeout
operation.

Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
diff --git a/drivers/watchdog/wm831x_wdt.c b/drivers/watchdog/wm831x_wdt.c
index b3e8a62..b1815c5 100644
--- a/drivers/watchdog/wm831x_wdt.c
+++ b/drivers/watchdog/wm831x_wdt.c
@@ -163,6 +163,8 @@
 			ret);
 	}
 
+	wdt_dev->timeout = timeout;
+
 	return ret;
 }