parisc: move dereference_function_descriptor to process.c

Commit deac93df26b20cf8438339b5935b5f5643bc30c9 fixed up printing
of %pF on parisc, but added the dereference_function_descriptor
prototype to module.c... this isn't a particularly wise idea as
module.c might not always be compiled.

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>