pwm: Use guards for pwm_lookup_lock instead of explicity mutex_lock + mutex_unlock

With the compiler caring for unlocking the mutex several functions can
be simplified. Benefit from that.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/28807cb5d9dbce66860f74829c0f57cd9c01373e.1719520143.git.u.kleine-koenig@baylibre.comSigned-off-by: Uwe Kleine-König <ukleinek@kernel.org>

drivers/pwm/core.c

@@ -1343,14 +1343,12 @@ static LIST_HEAD(pwm_lookup_list);
  */
 void pwm_add_table(struct pwm_lookup *table, size_t num)
 {
-	mutex_lock(&pwm_lookup_lock);
+	guard(mutex)(&pwm_lookup_lock);
 
 	while (num--) {
 		list_add_tail(&table->list, &pwm_lookup_list);
 		table++;
 	}
-
-	mutex_unlock(&pwm_lookup_lock);
 }
 
 /**
@@ -1360,14 +1358,12 @@ void pwm_add_table(struct pwm_lookup *table, size_t num)
  */
 void pwm_remove_table(struct pwm_lookup *table, size_t num)
 {
-	mutex_lock(&pwm_lookup_lock);
+	guard(mutex)(&pwm_lookup_lock);
 
 	while (num--) {
 		list_del(&table->list);
 		table++;
 	}
-
-	mutex_unlock(&pwm_lookup_lock);
 }
 
 /**
@@ -1428,8 +1424,7 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id)
 	 * Then we take the most specific entry - with the following order
 	 * of precedence: dev+con > dev only > con only.
 	 */
-	mutex_lock(&pwm_lookup_lock);
-
+	scoped_guard(mutex, &pwm_lookup_lock)
 		list_for_each_entry(p, &pwm_lookup_list, list) {
 			match = 0;
 
@@ -1457,8 +1452,6 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id)
 			}
 		}
 
-	mutex_unlock(&pwm_lookup_lock);
-
 	if (!chosen)
 		return ERR_PTR(-ENODEV);