test/crypto: fix stats test

test/crypto: fix stats test

ut_setup / ut_teardown are invoked for each test case by test framework.
The call inside test_stats is unnecessary and even incorrect.
This caused double free of objects such as crypto operation structure.
Trapped the issue when RTE_LIBRTE_MEMPOOL_DEBUG was enabled.
Fix issue by removing ut_setup / ut_teardown from test case implementation.

Fixes: 202d375c60bc ("app/test: add cryptodev unit and performance tests")
Cc: stable@dpdk.org
Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
Tested-by: Adam Dybkowski <adamx.dybkowski@intel.com>