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>