btrfs: drop unused parameter from btrfs_release_path

parameter tree root it's not used since commit
5f39d397dfbe140a14edecd4e73c34ce23c4f9ee ("Btrfs: Create extent_buffer
interface for large blocksizes")

Signed-off-by: David Sterba <dsterba@suse.cz>
diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c
index 992ab42..3b580ee 100644
--- a/fs/btrfs/tree-defrag.c
+++ b/fs/btrfs/tree-defrag.c
@@ -97,7 +97,7 @@
 		ret = 0;
 		goto out;
 	}
-	btrfs_release_path(root, path);
+	btrfs_release_path(path);
 	wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
 
 	if (wret < 0) {