ARM: integrator: impd1: Use GPIO_LOOKUP() helper macro

impd1_probe() fills in the GPIO lookup table by manually populating an
array of gpiod_lookup structures.  Use the existing GPIO_LOOKUP() helper
macro instead, to relax a dependency on the gpiod_lookup structure's
member names.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20200324135653.6676-1-geert+renesas@glider.be


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>