openrisc: require gpiolib

The recent move to GPIO descriptors breaks the OpenRISC build.  Requiring
gpiolib resolves this; using gpiolib exclusively is also the recommended
way forward for all arches by the developers working on these GPIO changes.
The non-gpiolib implementation for OpenRISC never worked anyway...

Signed-off-by: Jonas Bonn <jonas@southpole.se>
1 file changed