pwm: stm32: Add error messages in .probe()'s error paths

Giving an indication about the problem if probing a device fails is a
nice move. Do that for the stm32 pwm driver.
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20240315145443.982807-2-u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/pwm-stm32.c

@@ -648,11 +648,13 @@ static int stm32_pwm_probe(struct platform_device *pdev)
 	priv->max_arr = ddata->max_arr;
 
 	if (!priv->regmap || !priv->clk)
-		return -EINVAL;
+		return dev_err_probe(dev, -EINVAL, "Failed to get %s\n",
+				     priv->regmap ? "clk" : "regmap");
 
 	ret = stm32_pwm_probe_breakinputs(priv, np);
 	if (ret)
-		return ret;
+		return dev_err_probe(dev, ret,
+				     "Failed to configure breakinputs\n");
 
 	stm32_pwm_detect_complementary(priv);
 
@@ -664,7 +666,8 @@ static int stm32_pwm_probe(struct platform_device *pdev)
 
 	ret = devm_pwmchip_add(dev, chip);
 	if (ret < 0)
-		return ret;
+		return dev_err_probe(dev, ret,
+				     "Failed to register pwmchip\n");
 
 	platform_set_drvdata(pdev, chip);