btrfs: drop unused extent_op arg from btrfs_add_delayed_data_ref

btrfs_add_delayed_data_ref is always called with a NULL extent_op,
so let's drop the argument.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index dcd2e79..42a3bfd 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2089,7 +2089,7 @@
 		ret = btrfs_add_delayed_data_ref(fs_info, trans, bytenr,
 					num_bytes, parent, root_objectid,
 					owner, offset, 0,
-					BTRFS_ADD_DELAYED_REF, NULL);
+					BTRFS_ADD_DELAYED_REF);
 	}
 	return ret;
 }
@@ -7244,7 +7244,7 @@
 						num_bytes,
 						parent, root_objectid, owner,
 						offset, 0,
-						BTRFS_DROP_DELAYED_REF, NULL);
+						BTRFS_DROP_DELAYED_REF);
 	}
 	return ret;
 }
@@ -8194,8 +8194,7 @@
 	ret = btrfs_add_delayed_data_ref(fs_info, trans, ins->objectid,
 					 ins->offset, 0,
 					 root_objectid, owner, offset,
-					 ram_bytes, BTRFS_ADD_DELAYED_EXTENT,
-					 NULL);
+					 ram_bytes, BTRFS_ADD_DELAYED_EXTENT);
 	return ret;
 }