pwm: ab8500: Make use of devm_pwmchip_alloc() function

This prepares the pwm-ab8500 driver to further changes of the pwm core
outlined in the commit introducing devm_pwmchip_alloc(). There is no
intended semantical change and the driver should behave as before.

Link: https://lore.kernel.org/r/9c952baafe7e53c482adf23215138724b61e376b.1707900770.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/pwm-ab8500.c

@@ -24,13 +24,12 @@
 #define AB8500_PWM_CLKRATE 9600000
 
 struct ab8500_pwm_chip {
-	struct pwm_chip chip;
 	unsigned int hwid;
 };
 
 static struct ab8500_pwm_chip *ab8500_pwm_from_chip(struct pwm_chip *chip)
 {
-	return container_of(chip, struct ab8500_pwm_chip, chip);
+	return pwmchip_get_drvdata(chip);
 }
 
 static int ab8500_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
@@ -196,14 +195,13 @@ static int ab8500_pwm_probe(struct platform_device *pdev)
 	 * Nothing to be done in probe, this is required to get the
 	 * device which is required for ab8500 read and write
 	 */
-	ab8500 = devm_kzalloc(&pdev->dev, sizeof(*ab8500), GFP_KERNEL);
-	if (ab8500 == NULL)
-		return -ENOMEM;
+	chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*ab8500));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+
+	ab8500 = ab8500_pwm_from_chip(chip);
 
-	chip = &ab8500->chip;
-	chip->dev = &pdev->dev;
 	chip->ops = &ab8500_pwm_ops;
-	chip->npwm = 1;
 	ab8500->hwid = pdev->id - 1;
 
 	err = devm_pwmchip_add(&pdev->dev, chip);