ARM: ux500: register LP5521 LEDs in the device tree

Based on pending device tree support in the LP55xx drivers
we can add the correct LED and channel configuration from the
ux500 device tree for all HREF variants.

Cc: Bryan Wu <cooloney@gmail.com>
Acked-by: Milo Kim <Milo.Kim@ti.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>