of: remove undefined request_OF_resource & release_OF_resource

Neither request_OF_resource or release_OF_resource are defined
anywhere.  Remove the declarations.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Michal Simek <monstr@monstr.eu>