nvme: lightnvm: frees wrong cmd structure

When struct nvme_request was introduced, the nvme_nvm_submit_io was
converted to the new interface. The interface moves nvme_nvm_command
data structure into the struct request pdu. On io completion, rq->cmd is
freed, which should have been the dereferenced pdu nvme_request->cmd.

Fixes: d49187e97e94 "nvme: introduce struct nvme_request"
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/nvme/host/lightnvm.c

@@ -477,7 +477,7 @@ static void nvme_nvm_end_io(struct request *rq, int error)
 	rqd->ppa_status = nvme_req(rq)->result.u64;
 	nvm_end_io(rqd, error);
 
-	kfree(rq->cmd);
+	kfree(nvme_req(rq)->cmd);
 	blk_mq_free_request(rq);
 }