leds-lp5523: add new device id for LP55231

To support LP55231 device, the device id is added. Additionally,
the i2c driver name is changed from lp5523 to lp5523x.

Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: Bryan Wu <bryan.wu@canonical.com>