lightnvm: move rq->error to nvm_rq->error

Instead of passing request error into the LightNVM modules, incorporate
it into the nvm_rq.

Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
index cd674af..dad84dd 100644
--- a/drivers/lightnvm/core.c
+++ b/drivers/lightnvm/core.c
@@ -291,7 +291,8 @@
 
 void nvm_end_io(struct nvm_rq *rqd, int error)
 {
-	rqd->end_io(rqd, error);
+	rqd->error = error;
+	rqd->end_io(rqd);
 }
 EXPORT_SYMBOL(nvm_end_io);