pwm: bcm-kona: 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/f0086ed37f30c4d25bf226e722f5ae52a73974d9.1707900770.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/pwm-bcm-kona.c

@@ -164,7 +164,7 @@ static int kona_pwmc_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	ret = clk_prepare_enable(kp->clk);
 	if (ret < 0) {
-		dev_err(chip->dev, "failed to enable clock: %d\n", ret);
+		dev_err(pwmchip_parent(chip), "failed to enable clock: %d\n", ret);
 		return ret;
 	}
 
@@ -193,7 +193,7 @@ static int kona_pwmc_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 
 	ret = clk_prepare_enable(kp->clk);
 	if (ret < 0) {
-		dev_err(chip->dev, "failed to enable clock: %d\n", ret);
+		dev_err(pwmchip_parent(chip), "failed to enable clock: %d\n", ret);
 		return ret;
 	}