gpio: pca953x: Print the error code on read/write failures

Print the error code in the pca953x_write_regs() and pca953x_read_regs()
functions to help debugging.
Suggested-by: Russell King (Oracle) <linux@armlinux.org.uk>
Signed-off-by: Fabio Estevam <festevam@denx.de>
Link: https://lore.kernel.org/r/20240821114202.2072220-1-festevam@gmail.comSigned-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/gpio-pca953x.c

@@ -498,7 +498,7 @@ static int pca953x_write_regs(struct pca953x_chip *chip, int reg, unsigned long
 
 	ret = regmap_bulk_write(chip->regmap, regaddr, value, NBANK(chip));
 	if (ret < 0) {
-		dev_err(&chip->client->dev, "failed writing register\n");
+		dev_err(&chip->client->dev, "failed writing register: %d\n", ret);
 		return ret;
 	}
 
@@ -513,7 +513,7 @@ static int pca953x_read_regs(struct pca953x_chip *chip, int reg, unsigned long *
 
 	ret = regmap_bulk_read(chip->regmap, regaddr, value, NBANK(chip));
 	if (ret < 0) {
-		dev_err(&chip->client->dev, "failed reading register\n");
+		dev_err(&chip->client->dev, "failed reading register: %d\n", ret);
 		return ret;
 	}