gpio0 not accessable by user

[jost]

Hi,
I'm using openwrt on an Olimex board with RT5350. But I guess, the problem is the same on all linux distros.
The gpio0, though not in the gpio-export of the .dts file, is by default exported and there's a folder gpio0 in /sys/class/gpio after bootup. I need gpio0 as an output in user-space, but
the direction can not be changed, it is always an input. ( For the Reset Button).
Export in the .dts file has no effect. I guess a kernel mode driver does the export.
Does anybody know which kernel mode driver does this export and where to find it and remove the export?
Thanks.