btrfs: remove max_active var from open_ctree

Introduced by 5cdc7ad337fb ("btrfs: Replace fs_info->workers with
btrfs_workqueue.") but obsoleted by 2a4581983f90 ("btrfs: factor
btrfs_init_workqueues() out of open_ctree()").

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

@@ -2389,7 +2389,6 @@ int open_ctree(struct super_block *sb,
 	int err = -EINVAL;
 	int num_backups_tried = 0;
 	int backup_index = 0;
-	u32 max_active;
 	int clear_free_space_tree = 0;
 
 	tree_root = fs_info->tree_root = btrfs_alloc_root(fs_info, GFP_KERNEL);
@@ -2698,8 +2697,6 @@ int open_ctree(struct super_block *sb,
 		goto fail_alloc;
 	}
 
-	max_active = fs_info->thread_pool_size;
-
 	ret = btrfs_init_workqueues(fs_info, fs_devices);
 	if (ret) {
 		err = ret;