examples/l3fwd: check service core reset result
examples/l3fwd: check service core reset result

Fix unchecked return values reported by coverity.

Coverity issue: 354235
Fixes: 8bd537e9c6cf ("examples/l3fwd: add service core setup based on caps")
Cc: stable@dpdk.org

Signed-off-by: Pavan Nikhilesh <8184a94f8f7778086ea0697cdb513b2e42813b09@marvell.com>

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