lightnvm: propagate right error code to target

If nvme_alloc_request fails, propagate the right error, instead of
assuming ENOMEM.

Signed-off-by: Javier González <[e-mail]>
Signed-off-by: Matias Bjørling <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/nvme/host/lightnvm.c

···
 	rq = nvme_alloc_request(q, (struct nvme_command *)cmd, 0, NVME_QID_ANY);
 	if (IS_ERR(rq)) {
 		kfree(cmd);
-		return -ENOMEM;
+		return PTR_ERR(rq);
 	}
 	rq->cmd_flags &= ~REQ_FAILFAST_DRIVER;