leds: is31fl319x: Use devm_mutex_init()

Use devm_mutex_init() instead of hand-writing it.

This saves some LoC, improves readability and saves some space in the
generated .o file.

Before:
======
text data bss dec hex filename
20011 6752 128 26891 690b drivers/leds/leds-is31fl319x.o

After:
=====
text data bss dec hex filename
19715 6680 128 26523 679b drivers/leds/leds-is31fl319x.o

Signed-off-by: Christophe JAILLET <[e-mail]>
Link: https://lore.kernel.org/r/267aba6eab[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

drivers/leds/leds-is31fl319x.c

···
 	return dezibel / IS31FL3196_AUDIO_GAIN_DB_STEP;
 }
 
-static void is31f1319x_mutex_destroy(void *lock)
-{
-	mutex_destroy(lock);
-}
-
 static int is31fl319x_probe(struct i2c_client *client)
 {
 	struct is31fl319x_chip *is31;
···
 	if (!is31)
 		return -ENOMEM;
 
-	mutex_init(&is31->lock);
-	err = devm_add_action_or_reset(dev, is31f1319x_mutex_destroy, &is31->lock);
+	err = devm_mutex_init(dev, &is31->lock);
 	if (err)
 		return err;