leds-lp5523: use the i2c device id rather than fixed name

LP5523 driver supports both LP5523 and LP55231. The i2c device id
is one of the two - lp5523 or lp55231. So it's better to use
matching i2c device id while enumerating the device and naming LED
channels.

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