ARM: dts: BCM53573: Drop nonexistent "default-off" LED trigger

ARM: dts: BCM53573: Drop nonexistent "default-off" LED trigger

There is no such trigger documented or implemented in Linux. It was a
copy & paste mistake.

This fixes:
arch/arm/boot/dts/broadcom/bcm47189-luxul-xap-1440.dtb: leds: led-wlan:linux,default-trigger: 'oneOf' conditional failed, one must be fixed:
        'default-off' is not one of ['backlight', 'default-on', 'heartbeat', 'disk-activity', 'disk-read', 'disk-write', 'timer', 'pattern', 'audio-micmute', 'audio-mute', 'bluetooth-power', 'flash', 'kbd-capslock', 'mtd', 'nand-disk', 'none', 'torch', 'usb-gadget', 'usb-host', 'usbport']
        'default-off' does not match '^cpu[0-9]*$'
        'default-off' does not match '^hci[0-9]+-power$'
        'default-off' does not match '^mmc[0-9]+$'
        'default-off' does not match '^phy[0-9]+tx$'
        From schema: Documentation/devicetree/bindings/leds/leds-gpio.yaml

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20230707114004.2740-1-zajec5@gmail.com
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>