net/vhost: move statistics into a structure
net/vhost: move statistics into a structure

The patch moves all stats counters to a new defined struct vhost_stats
as follows, in order to manage all stats counters in a unified way and
simplify the subsequent function implementation(vhost_dev_xstats_reset).

Signed-off-by: Zhiyong Yang <fbdb847fac8e5e50b588eb93d9ff9fd811b7568c@intel.com>
Acked-by: Yuanhan Liu <5dcef21195e64c9c08aa779bb62b25e9133eaa33@linux.intel.com>

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