app/testpmd: fix MAC address after port reset

app/testpmd: fix MAC address after port reset

MAC address of each port in global variable ports hasn't been updated
after resetting. It was the initial one after resetting VF MAC address.
This patch gets correct port MAC address when starting port.

Fixes: a5279d25616d ("app/testpmd: check status of getting MAC address")
Cc: stable@dpdk.org
Signed-off-by: Yuying Zhang <yuying.zhang@intel.com>
Acked-by: Aman Deep Singh <aman.deep.singh@intel.com>
Acked-by: Xiaoyun Li <xiaoyun.li@intel.com>