imx_watchdog: always set minimal timeout in reset_cpu

The problem is that timeout bits in WCR register were leaved unchanged.
So previously set timeout value was applied and therefore 'reset'
command takes any value up to two minutes, depending on previous
watchdog settings, instead of minimal 0.5 seconds.

Signed-off-by: Andrey Skvortsov <andrej.skvortzov@gmail.com>
diff --git a/drivers/watchdog/imx_watchdog.c b/drivers/watchdog/imx_watchdog.c
index 0d77595..f9f8175 100644
--- a/drivers/watchdog/imx_watchdog.c
+++ b/drivers/watchdog/imx_watchdog.c
@@ -43,7 +43,7 @@
 {
 	struct watchdog_regs *wdog = (struct watchdog_regs *)WDOG1_BASE_ADDR;
 
-	clrsetbits_le16(&wdog->wcr, 0, WCR_WDE);
+	clrsetbits_le16(&wdog->wcr, WCR_WT_MSK, WCR_WDE);
 
 	writew(0x5555, &wdog->wsr);
 	writew(0xaaaa, &wdog->wsr);	/* load minimum 1/2 second timeout */
diff --git a/include/fsl_wdog.h b/include/fsl_wdog.h
index d15a70c..f698d4d 100644
--- a/include/fsl_wdog.h
+++ b/include/fsl_wdog.h
@@ -16,3 +16,4 @@
 #define WCR_WDT		0x08
 #define WCR_SRS		0x10
 #define SET_WCR_WT(x)	(x << 8)
+#define WCR_WT_MSK	SET_WCR_WT(0xFF)