pwm: img: 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 <wsa+renesas@sang-engineering.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-img.c

@@ -237,6 +237,11 @@ static int img_pwm_probe(struct platform_device *pdev)
 	}
 
 	clk_rate = clk_get_rate(pwm->pwm_clk);
+	if (!clk_rate) {
+		dev_err(&pdev->dev, "pwm clock has no frequency\n");
+		ret = -EINVAL;
+		goto disable_pwmclk;
+	}
 
 	/* The maximum input clock divider is 512 */
 	val = (u64)NSEC_PER_SEC * 512 * pwm->data->max_timebase;