Including arm/mv/gpio.c now depends on 'gpio' device. 'device gpio' was
added to all kernconf files of Marvell boards, except ARMADAXP (dummy
mv_gpio_res definition was removed) and ARMADA38X (not supported yet).
This commit allows to use generic files.mv on A38X.
Obtained from: Semihalf
Sponsored by: Stormshield
Submitted by: Bartosz Szczepanek <bsz@semihalf.com>