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/dir-item.c b/fs/btrfs/dir-item.c
index c62f02f..ab8afed 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -172,7 +172,7 @@
 		ret = 0;
 		goto out_free;
 	}
-	btrfs_release_path(root, path);
+	btrfs_release_path(path);
 
 	btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
 	key.offset = index;