pwm: crc: Make use of pwmchip_parent() accessor

struct pwm_chip::dev is about to change. To not have to touch this
driver in the same commit as struct pwm_chip::dev, use the accessor
function provided for exactly this purpose.

Link: https://lore.kernel.org/r/a41b62365295be9debd4a9aaa80ca87fca35b320.1707900770.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/pwm-crc.c

@@ -55,7 +55,7 @@ static int crc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			 const struct pwm_state *state)
 {
 	struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip);
-	struct device *dev = chip->dev;
+	struct device *dev = pwmchip_parent(chip);
 	int err;
 
 	if (state->period > PWM_MAX_PERIOD_NS) {
@@ -125,7 +125,7 @@ static int crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 			     struct pwm_state *state)
 {
 	struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip);
-	struct device *dev = chip->dev;
+	struct device *dev = pwmchip_parent(chip);
 	unsigned int clk_div, clk_div_reg, duty_cycle_reg;
 	int error;