drbd: fix local read error hung forever

The commit
    drbd: simplify retry path of failed READ requests
simplified it too much:
it just did not do anything for local read errors.

Add the missing req_may_be_completed_not_susp() to the
READ_COMPLETED_WITH_ERROR case.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_req.c

@@ -460,6 +460,7 @@ int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 		D_ASSERT(!(req->rq_state & RQ_NET_MASK));
 
 		__drbd_chk_io_error(mdev, false);
+		req_may_be_completed_not_susp(req, m);
 		break;
 
 	case QUEUE_FOR_NET_READ: