pwm: atmel-pwm: Do not unprepare clock after successful registration

When the PWM controller is registered successfully, the clock can not
unprepare, so fix it.
Signed-off-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-atmel.c

@@ -362,6 +362,8 @@ static int atmel_pwm_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, atmel_pwm);
 
+	return ret;
+
 unprepare_clk:
 	clk_unprepare(atmel_pwm->clk);
 	return ret;