btrfs_dev_stat_reset() is an overdo in terms of wrapping. So this patch
open codes btrfs_dev_stat_reset().
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>