pwm: tiecap: Make use of devm_pwmchip_alloc() function

This prepares the pwm-tegra 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/af7846109c0df225126c8e5cd186b89ace70afc0.1707900770.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/pwm-tiecap.c

@@ -32,7 +32,6 @@ struct ecap_context {
 };
 
 struct ecap_pwm_chip {
-	struct pwm_chip chip;
 	unsigned int clk_rate;
 	void __iomem *mmio_base;
 	struct ecap_context ctx;
@@ -40,7 +39,7 @@ struct ecap_pwm_chip {
 
 static inline struct ecap_pwm_chip *to_ecap_pwm_chip(struct pwm_chip *chip)
 {
-	return container_of(chip, struct ecap_pwm_chip, chip);
+	return pwmchip_get_drvdata(chip);
 }
 
 /*
@@ -222,9 +221,10 @@ static int ecap_pwm_probe(struct platform_device *pdev)
 	struct clk *clk;
 	int ret;
 
-	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
-	if (!pc)
-		return -ENOMEM;
+	chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*pc));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+	pc = to_ecap_pwm_chip(chip);
 
 	clk = devm_clk_get(&pdev->dev, "fck");
 	if (IS_ERR(clk)) {
@@ -245,10 +245,7 @@ static int ecap_pwm_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	chip = &pc->chip;
-	chip->dev = &pdev->dev;
 	chip->ops = &ecap_pwm_ops;
-	chip->npwm = 1;
 
 	pc->mmio_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(pc->mmio_base))