leds: mt6323: use struct led_init_data when registering

leds: mt6323: use struct led_init_data when registering

By using struct led_init_data when registering we do not need to parse
`label` DT property. Moreover `label` is deprecated and if it is not
present but `color` and `function` are, LED core will compose a name
from these properties instead.

Since init_data is passed with fwnode handle, we do not need to set
the of_node member of the newly created LED classdev.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Cc: Sean Wang <sean.wang@mediatek.com>
Cc: John Crispin <john@phrozen.org>
Cc: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>