ARM: davinci: Use GPIO lookup table for DA850 LEDs

This switches the DA850 board to use a GPIO lookup table to
look up the GPIO LEDs. Thanks to the offset handling when
we define GPIOs as an offset into the chip, we can drop
some complex code.

Tested-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>