xen/blocks: Return -EXX instead of -1

Lets return sensible values instead of -1.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 2b8650a9..ca3a414 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -996,7 +996,7 @@
 		be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
 	else {
 		xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
-		return -1;
+		return -ENOSYS;
 	}
 	err = xenbus_gather(XBT_NIL, dev->otherend,
 			    "feature-persistent", "%u",
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 8b0f3d9..ef5ce43 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -828,11 +828,11 @@
 	info->tag_set.driver_data = info;
 
 	if (blk_mq_alloc_tag_set(&info->tag_set))
-		return -1;
+		return -EINVAL;
 	rq = blk_mq_init_queue(&info->tag_set);
 	if (IS_ERR(rq)) {
 		blk_mq_free_tag_set(&info->tag_set);
-		return -1;
+		return PTR_ERR(rq);
 	}
 
 	queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);