pwm: sl28cpld: fix getting driver data in pwm callbacks

Currently .get_state() and .apply() use dev_get_drvdata() on the struct
device related to the pwm chip. This only works after .probe() called
platform_set_drvdata() which in this driver happens only after
pwmchip_add() and so comes possibly too late.

Instead of setting the driver data earlier use the traditional
container_of approach as this way the driver data is conceptually and
computational nearer.

Fixes: 9db33d221efc ("pwm: Add support for sl28cpld PWM controller")
Tested-by: Michael Walle <[e-mail]>
Signed-off-by: Uwe Kleine-König <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/pwm/pwm-sl28cpld.c

···
 	struct regmap *regmap;
 	u32 offset;
 };
+#define sl28cpld_pwm_from_chip(_chip) \
+	container_of(_chip, struct sl28cpld_pwm, pwm_chip)
 
 static void sl28cpld_pwm_get_state(struct pwm_chip *chip,
 				   struct pwm_device *pwm,
 				   struct pwm_state *state)
 {
-	struct sl28cpld_pwm *priv = dev_get_drvdata(chip->dev);
+	struct sl28cpld_pwm *priv = sl28cpld_pwm_from_chip(chip);
 	unsigned int reg;
 	int prescaler;
 
···
 static int sl28cpld_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			      const struct pwm_state *state)
 {
-	struct sl28cpld_pwm *priv = dev_get_drvdata(chip->dev);
+	struct sl28cpld_pwm *priv = sl28cpld_pwm_from_chip(chip);
 	unsigned int cycle, prescaler;
 	bool write_duty_cycle_first;
 	int ret;