pwm: lpss: Release runtime-pm reference from the driver's remove callback

For each pwm output which gets enabled through pwm_lpss_apply(), we do a
pm_runtime_get_sync().

This commit adds pm_runtime_put() calls to pwm_lpss_remove() to balance
these when the driver gets removed with some of the outputs still enabled.

Fixes: f080be27 ("pwm: lpss: Add support for runtime PM")
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>