test/ring_perf: use compiler atomic builtins for lcores sync
test/ring_perf: use compiler atomic builtins for lcores sync

Convert rte_atomic usages to compiler atomic built-ins
for lcores sync in ring_perf test cases.

Signed-off-by: Joyce Kong <c01c57df07e2f34c67ea70652554926ebc164737@arm.com>
Reviewed-by: Ruifeng Wang <a548d51fbc42485a8ba807711a537e88c2b59dd2@arm.com>
Reviewed-by: Honnappa Nagarahalli <01ccf438b971cc1d8919c8a7f18443cae9429d8b@arm.com>

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