pwm: iqs620a: Create a wrapper for converting a pwm_chip to driver data

There is no semantic change. The new function just implements what was
open-coded twice in the driver before.

Link: https://lore.kernel.org/r/cc7ab547b4c4b79456b548aa72205bcf4476db8c.1707900770.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/pwm-iqs620a.c

@@ -40,6 +40,11 @@ struct iqs620_pwm_private {
 	unsigned int duty_scale;
 };
 
+static inline struct iqs620_pwm_private *iqs620_pwm_from_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct iqs620_pwm_private, chip);
+}
+
 static int iqs620_pwm_init(struct iqs620_pwm_private *iqs620_pwm,
 			   unsigned int duty_scale)
 {
@@ -73,7 +78,7 @@ static int iqs620_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	if (state->period < IQS620_PWM_PERIOD_NS)
 		return -EINVAL;
 
-	iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
+	iqs620_pwm = iqs620_pwm_from_chip(chip);
 
 	/*
 	 * The duty cycle generated by the device is calculated as follows:
@@ -109,7 +114,7 @@ static int iqs620_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 {
 	struct iqs620_pwm_private *iqs620_pwm;
 
-	iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
+	iqs620_pwm = iqs620_pwm_from_chip(chip);
 
 	mutex_lock(&iqs620_pwm->lock);