[WATCHDOG] fix clk_get() error check

The return value of clk_get() should be checked by IS_ERR().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --git a/drivers/char/watchdog/s3c2410_wdt.c b/drivers/char/watchdog/s3c2410_wdt.c
index d3c0737..5a5cc2a 100644
--- a/drivers/char/watchdog/s3c2410_wdt.c
+++ b/drivers/char/watchdog/s3c2410_wdt.c
@@ -393,9 +393,9 @@
 	}
 
 	wdt_clock = clk_get(&pdev->dev, "watchdog");
-	if (wdt_clock == NULL) {
+	if (IS_ERR(wdt_clock)) {
 		printk(KERN_INFO PFX "failed to find watchdog clock source\n");
-		ret =  -ENOENT;
+		ret = PTR_ERR(wdt_clock);
 		goto err_irq;
 	}