pwm: Fix device reference leak

Make sure to drop the reference to the parent device taken by
class_find_device() after "unexporting" any children when deregistering
a PWM chip.

Fixes: 0733424c9ba9 ("pwm: Unexport children before chip removal")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/sysfs.c

@@ -425,6 +425,8 @@ void pwmchip_sysfs_unexport_children(struct pwm_chip *chip)
 		if (test_bit(PWMF_EXPORTED, &pwm->flags))
 			pwm_unexport_child(parent, pwm);
 	}
+
+	put_device(parent);
 }
 
 static int __init pwm_sysfs_init(void)