net/iavf: fix Rx total stats
net/iavf: fix Rx total stats

Rx total stats is the total number of successfully received packets,
so exclude the number of rx_discards for Rx total stats.

Fixes: f4a41a6953af ("net/avf: support stats")
Cc: stable@dpdk.org

Signed-off-by: Jiaqi Min <2f7a5ac4ebfaeb41e216ea73c8554e948dede266@intel.com>
Acked-by: Jingjing Wu <64d28b617c3b4840f5ded1bfa611cba7fadfe5c7@intel.com>

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