pwm: lpss: Remove ->free() callback

The LPSS PWM driver calls pwm_lpss_disable() when the PWM device is
released (for example unexported from sysfs). This in turn calls
pm_runtime_put() which makes runtime PM count to be unbalanced if the
device has not been enabled at this point.

This is easy to reproduce:

  # cd /sys/class/pwm/pwmchip0
  # echo 0 > export
  # echo 0 > unexport

The count is unbalanced and prevents the PWM device from being powered on
next time.

Fix this by removing ->free() callback. There are no resources to be
released anyway.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-lpss.c

@@ -135,7 +135,6 @@ static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 }
 
 static const struct pwm_ops pwm_lpss_ops = {
-	.free = pwm_lpss_disable,
 	.config = pwm_lpss_config,
 	.enable = pwm_lpss_enable,
 	.disable = pwm_lpss_disable,