fq_codel: fix TCA_FQ_CODEL_DROP_BATCH_SIZE sanity checks

My intent was to not let users set a zero drop_batch_size,
it seems I once again messed with min()/max().

Fixes: 9d18562a ("fq_codel: add batch ability to fq_codel_drop()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>