leds: wago-m4: use DT label as-is for LED class device name

Set init_data.devicename = NULL in the DT child-node registration path
so that led_compose_name() uses the fwnode 'label' property directly as
the LED class device name, without prepending the driver name.

This changes the sysfs entries from:
  /sys/class/leds/wago-m4-led-wrapper:sys
to:
  /sys/class/leds/sys

matching the naming convention of the PCA9552 multicolor LED groups.

Signed-off-by: Heinrich Toews <ht@twx-software.de>

drivers/leds/rgb/wago-m4-led-wrapper.c

@@ -441,7 +441,7 @@ static int wago_led_register_leds(struct wago_m4_led_priv *priv)
 			wago_led_init_subled(led);
 
 			init_data.fwnode            = child;
-			init_data.devicename        = DRIVER_NAME;
+			init_data.devicename        = NULL;
 			init_data.devname_mandatory = false;
 
 			ret = devm_led_classdev_multicolor_register_ext(