[SG] Update drivers to use sg helpers

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/block/sunvdc.c b/drivers/block/sunvdc.c
index 317a790..7276f7d 100644
--- a/drivers/block/sunvdc.c
+++ b/drivers/block/sunvdc.c
@@ -388,6 +388,7 @@
 		op = VD_OP_BWRITE;
 	}
 
+	sg_init_table(sg, port->ring_cookies);
 	nsg = blk_rq_map_sg(req->q, req, sg);
 
 	len = 0;