arm64: dts: mediatek: mt7988a-bpi-r4: add gpio leds

arm64: dts: mediatek: mt7988a-bpi-r4: add gpio leds

Bananapi R4 has a green and a blue led which can be switched by gpio.
Green led is for running state so default on.

Green led also shares pin with eeprom writeprotect where led off allows
writing to eeprom.

Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20250706132213.20412-14-linux@fw-web.de
[Angelo: Fixed missing dt-bindings/leds/common.h header inclusion]
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>