pwm: dwc: use pm_sleep_ptr() macro

Since we don't have runtime PM handles here, we should be using
pm_sleep_ptr() macro, so that the compiler can discard it in case
CONFIG_PM_SLEEP=n.

Fixes: 30b5b066

 ("pwm: dwc: Use DEFINE_SIMPLE_DEV_PM_OPS for PM functions")
Signed-off-by: Raag Jadav <raag.jadav@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240212130247.9985-2-raag.jadav@intel.com
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>