xfs: initialise args->total for parent pointer updates

In the Linux kernel, the following vulnerability has been resolved: xfs: initialise args->total for parent pointer updates xfs_parent_da_args_init() builds an xfs_da_args from a zeroed xfs_parent_args (kmem_cache_zalloc), leaving args->total == 0. xfs_da_grow_inode_int() treats that field as a running block reservation and subtracts from it; because it is an xfs_extlen_t (uint32_t), the first attr-fork growth wraps it to ~0U. That defeats the free-space check in xfs_alloc_space_available(), and when it coincides with an AG that has exactly zero available blocks the allocation is clamped to maxlen 0 and returns -ENOSPC, which xfs_defer_finish_noroll() escalates to a filesystem shutdown. Set args->total the way the log recovery path does (xfs_attri_recover_work(), xfs_attr_item.c:706), in the add and replace paths that can grow the fork. Removals and lookups never grow it, so they leave the field alone, matching that switch.