rte_eth_stats_get is to get physical device statistics. Without
return status, caller does not know whether function fails or not
(i.e. invalid port_id, driver has no stats_get callback). Caller
cannot differiente normal 0 stats or error case. This fix adds
a return status to the function.
Signed-off-by: Jia Yu <jyu@vmware.com>
Acked-by: Helin Zhang <helin.zhang@intel.com>