test/reorder: fix freeing mbuf twice

test/reorder: fix freeing mbuf twice

mbufs are being freed twice in error, once in rte_mempool_put_bulk()
and then in rte_reorder_free(). Refactor the code so that we use
rte_reorder_free() to free mbufs in the reorder buffer, and use
rte_pktmbuf_free() to free any unused or drained mbufs.

Fixes: d0c9b58d71 ("app/test: new reorder unit test")
Cc: stable@dpdk.org
Signed-off-by: Reshma Pattan <reshma.pattan@intel.com>
Reviewed-by: David Hunt <david.hunt@intel.com>