pwm: stm32-lp: Make use of devm_pwmchip_alloc() function

This prepares the pwm-stm32-lp 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/04af7b3d00bc932dd025200a3bf74527c29ca47a.1707900770.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/pwm-stm32-lp.c

@@ -18,14 +18,13 @@
 #include <linux/pwm.h>
 
 struct stm32_pwm_lp {
-	struct pwm_chip chip;
 	struct clk *clk;
 	struct regmap *regmap;
 };
 
 static inline struct stm32_pwm_lp *to_stm32_pwm_lp(struct pwm_chip *chip)
 {
-	return container_of(chip, struct stm32_pwm_lp, chip);
+	return pwmchip_get_drvdata(chip);
 }
 
 /* STM32 Low-Power Timer is preceded by a configurable power-of-2 prescaler */
@@ -200,16 +199,14 @@ static int stm32_pwm_lp_probe(struct platform_device *pdev)
 	struct pwm_chip *chip;
 	int ret;
 
-	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
-	if (!priv)
-		return -ENOMEM;
+	chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*priv));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+	priv = to_stm32_pwm_lp(chip);
 
 	priv->regmap = ddata->regmap;
 	priv->clk = ddata->clk;
-	chip = &priv->chip;
-	chip->dev = &pdev->dev;
 	chip->ops = &stm32_pwm_lp_ops;
-	chip->npwm = 1;
 
 	ret = devm_pwmchip_add(&pdev->dev, chip);
 	if (ret < 0)