wdt: designware: fix timeout calculation due to expecting KHz

The timeout calculation is based on the clk being in KHz but
the clk api returns the clk value in Hz. Convert this to KHz
to calculate the correct timeout value.

Signed-off-by: Jack Mitchell <ml@embed.me.uk>
diff --git a/drivers/watchdog/designware_wdt.c b/drivers/watchdog/designware_wdt.c
index 12f09a7..7caa6c5 100644
--- a/drivers/watchdog/designware_wdt.c
+++ b/drivers/watchdog/designware_wdt.c
@@ -130,7 +130,7 @@
 	if (ret)
 		return ret;
 
-	priv->clk_khz = clk_get_rate(&clk);
+	priv->clk_khz = clk_get_rate(&clk) / 1000;
 	if (!priv->clk_khz)
 		return -EINVAL;
 #else