TWL4030: make LEDs selectable for twl4030_led_init()

Not all boards have both LEDs hooked, so enabling both on
boards with single LED will just waste power. Make it
possible to choose LEDs by adding argument to
twl4030_led_init().

Using this turn on only LEDB for pandora, leave both LEDs
on for all other boards, as it was before this patch.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>