btrfs: drop unused parameter transaction from alloc_log_tree()

The function got split in commit 6ab6ebb ("btrfs: split
alloc_log_tree()") and since then transaction parameter has been unused.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

@@ -917,8 +917,7 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 	return ERR_PTR(ret);
 }
 
-static struct btrfs_root *alloc_log_tree(struct btrfs_trans_handle *trans,
-					 struct btrfs_fs_info *fs_info)
+static struct btrfs_root *alloc_log_tree(struct btrfs_fs_info *fs_info)
 {
 	struct btrfs_root *root;
 
@@ -966,7 +965,7 @@ int btrfs_init_log_root_tree(struct btrfs_trans_handle *trans,
 {
 	struct btrfs_root *log_root;
 
-	log_root = alloc_log_tree(trans, fs_info);
+	log_root = alloc_log_tree(fs_info);
 	if (IS_ERR(log_root))
 		return PTR_ERR(log_root);
 
@@ -992,7 +991,7 @@ int btrfs_add_log_tree(struct btrfs_trans_handle *trans,
 	struct btrfs_inode_item *inode_item;
 	int ret;
 
-	log_root = alloc_log_tree(trans, fs_info);
+	log_root = alloc_log_tree(fs_info);
 	if (IS_ERR(log_root))
 		return PTR_ERR(log_root);