test/distributor: fix spurious failure
test/distributor: fix spurious failure

Sanity test could spuriously fail with reporting flush count error.
It was caused by worker stat coherent issue between distributor and
worker thread.
Fix this issue by using atomic operations to update worker stat.

Fixes: c3eabff124e6 ("distributor: add unit tests")
Cc: stable@dpdk.org

Signed-off-by: Ruifeng Wang <a548d51fbc42485a8ba807711a537e88c2b59dd2@arm.com>
Reviewed-by: Gavin Hu <207ee22c2cf71e20c5b5df8395050c07c07d8709@arm.com>
Acked-by: David Hunt <763be7c8e0ad91e03160e7aed76d5cd41534e2f9@intel.com>

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