watchdog: atlas7_wdt: test clock rate to avoid division by 0

The clk API may return 0 on clk_get_rate, so we should check the result before
using it as a divisor.

Signed-off-by: Wolfram Sang <[e-mail]>
Signed-off-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/atlas7_wdt.c

···
 	writel(0, wdt->base + ATLAS7_WDT_CNT_CTRL);
 
 	wdt->tick_rate = clk_get_rate(clk);
+	if (!wdt->tick_rate) {
+		ret = -EINVAL;
+		goto err1;
+	}
+
 	wdt->clk = clk;
 	atlas7_wdd.min_timeout = 1;
 	atlas7_wdd.max_timeout = UINT_MAX / wdt->tick_rate;