[WATCHDOG] trivial fix two returns in void functions

This patch fixes two returns in the TI Davinci and
PNX4008 in void functions.

Signed-off-by: Florian Fainelli <florian.fainelli@telecomint.eu>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --git a/drivers/watchdog/davinci_wdt.c b/drivers/watchdog/davinci_wdt.c
index 19db530..e49a36c 100644
--- a/drivers/watchdog/davinci_wdt.c
+++ b/drivers/watchdog/davinci_wdt.c
@@ -262,7 +262,7 @@
 
 static void __exit davinci_wdt_exit(void)
 {
-	return platform_driver_unregister(&platform_wdt_driver);
+	platform_driver_unregister(&platform_wdt_driver);
 }
 
 module_init(davinci_wdt_init);