gpio: pca9570: use lock guards

Shrink the code by a couple lines and improve lock management by using
lock guards from cleanup.h.

Reviewed-by: Linus Walleij <[e-mail]>
Signed-off-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Bartosz Golaszewski <[e-mail]>

drivers/gpio/gpio-pca9570.c

···
  */
 
 #include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/device/devres.h>
 #include <linux/errno.h>
 #include <linux/gpio/driver.h>
···
 	u8 buffer;
 	int ret;
 
-	mutex_lock(&gpio->lock);
+	guard(mutex)(&gpio->lock);
 
 	buffer = gpio->out;
 	if (value)
···
 
 	ret = pca9570_write(gpio, buffer);
 	if (ret)
-		goto out;
+		return ret;
 
 	gpio->out = buffer;
 
-out:
-	mutex_unlock(&gpio->lock);
-	return ret;
+	return 0;
 }
 
 static int pca9570_probe(struct i2c_client *client)