orangefs: always take op->lock inside the request_list_lock

Take the op lock inside the request_list_lock when adding new entries to
the waitqueue, as we take it inside in other places aswell.

This is just the quick fix, we probably don't need to hold the op lock
at all for the list addition.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>