wdt: dw: Enable the clock before using it

The watchdog won't work if the clock isn't enabled.

Fixes: cf89ef8d10f240554541c20b2e1bdcdd58d1d7e6
Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/watchdog/designware_wdt.c b/drivers/watchdog/designware_wdt.c
index a65487d..709a67f 100644
--- a/drivers/watchdog/designware_wdt.c
+++ b/drivers/watchdog/designware_wdt.c
@@ -129,6 +129,10 @@
 	if (ret)
 		return ret;
 
+	ret = clk_enable(&clk);
+	if (ret)
+		return ret;
+
 	priv->clk_khz = clk_get_rate(&clk) / 1000;
 	if (!priv->clk_khz)
 		return -EINVAL;