btrfs: compression: let workspace manager cleanup take only the type

With the access to the workspace structures, we can look it up together
with the compression ops inside the workspace manager cleanup helper.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/zlib.c

@@ -31,7 +31,7 @@ static struct workspace_manager wsm;
 
 static void zlib_cleanup_workspace_manager(void)
 {
-	btrfs_cleanup_workspace_manager(&wsm);
+	btrfs_cleanup_workspace_manager(BTRFS_COMPRESS_ZLIB);
 }
 
 static struct list_head *zlib_get_workspace(unsigned int level)