test/ring: fix statistics in bulk enq/dequeue
test/ring: fix statistics in bulk enq/dequeue

In size 32 bulk ring enq/dequeue performance test, the "Total count"
statistics is incorrect. For example, running the test on lcore 25 and
lcore 26, the output is as follows:

The test command:
$sudo ./arm64-armv8a-linuxapp-gcc/app/test -l 25-26
RTE>>ring_perf_autotest

Bulk enq/dequeue count on size 32
Core [25] count = 288268
Core [26] count = 288281
Total count (size: 32): 1066323

Fixed it by reset the counter at the beginning of each loop. The
revised output is as follows:

Bulk enq/dequeue count on size 32
Core [25] count = 285643
Core [26] count = 285688
Total count (size: 32): 571331

Fixes: 759cf9b5632c ("test/ring: enhance mp/mc coverage")
Cc: stable@dpdk.org

Signed-off-by: Feifei Wang <2493857810266eaae720c9869c8b9d6ce45d3739@arm.com>
Reviewed-by: Ruifeng Wang <a548d51fbc42485a8ba807711a537e88c2b59dd2@arm.com>
Reviewed-by: Phil Yang <5a9b6465c065ff0e1fd5d2cb9eb2185e82f34247@arm.com>
Acked-by: Konstantin Ananyev <cbd5212b59ab42a210d72992d23a3aa17cfd3eaf@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk