pwm: dwc-core: Make use of pwmchip_parent() accessor

struct pwm_chip::dev is about to change. To not have to touch this
driver in the same commit as struct pwm_chip::dev, use the accessor
function provided for exactly this purpose.

Link: https://lore.kernel.org/r/5240ba82ac227e3723678041bd69b9c7a9e3db43.1707900770.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/pwm-dwc-core.c

@@ -105,12 +105,12 @@ static int dwc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	if (state->enabled) {
 		if (!pwm->state.enabled)
-			pm_runtime_get_sync(chip->dev);
+			pm_runtime_get_sync(pwmchip_parent(chip));
 		return __dwc_pwm_configure_timer(dwc, pwm, state);
 	} else {
 		if (pwm->state.enabled) {
 			__dwc_pwm_set_enable(dwc, pwm->hwpwm, false);
-			pm_runtime_put_sync(chip->dev);
+			pm_runtime_put_sync(pwmchip_parent(chip));
 		}
 	}
 
@@ -124,7 +124,7 @@ static int dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	u64 duty, period;
 	u32 ctrl, ld, ld2;
 
-	pm_runtime_get_sync(chip->dev);
+	pm_runtime_get_sync(pwmchip_parent(chip));
 
 	ctrl = dwc_pwm_readl(dwc, DWC_TIM_CTRL(pwm->hwpwm));
 	ld = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT(pwm->hwpwm));
@@ -149,7 +149,7 @@ static int dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	state->period = period;
 	state->duty_cycle = duty;
 
-	pm_runtime_put_sync(chip->dev);
+	pm_runtime_put_sync(pwmchip_parent(chip));
 
 	return 0;
 }