m68knommu: simplify the ColdFire 520x GPIO struct setup

The GPIO data struct setup is now the only remaining code in the platform
gpio.c file. So move it to the platform config.c code and remove the gpio.c
file.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Acked-by: Steven King <sfking@fdwdc.com>