btrfs: make btrfs_set_root_node void

This is fairly trivial - btrfs_set_root_node() - always returns zero so we
can just make it void.  All callers ignore the return code now anyway.  I
also made sure to check that none of the functions that
btrfs_set_root_node() calls returns an error that we might have needed to
catch and pass back.

Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 7ac4d25..34ce414 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2406,8 +2406,8 @@
 			 btrfs_root_item *item, struct btrfs_key *key);
 int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid);
 int btrfs_find_orphan_roots(struct btrfs_root *tree_root);
-int btrfs_set_root_node(struct btrfs_root_item *item,
-			struct extent_buffer *node);
+void btrfs_set_root_node(struct btrfs_root_item *item,
+			 struct extent_buffer *node);
 void btrfs_check_and_init_root_item(struct btrfs_root_item *item);
 
 /* dir-item.c */