app/testpmd: show MAC addresses added to a port

app/testpmd: show MAC addresses added to a port

Patch adds a runtime function to display the unicast and
multicast MAC addresses added to a port.

Syntax:
	show port (port_id) macs|mcast_macs

Usage:
testpmd> show port 0 macs
Number of MAC address added: 1
  B0:26:28:7F:F5:C1
testpmd>
testpmd> show port 0 mcast_macs
Number of Multicast MAC address added: 0
testpmd>
testpmd> mac_addr add 0 B0:26:28:7F:22:33
testpmd> mac_addr add 0 B0:26:28:7F:22:34
testpmd> show port 0 macs
Number of MAC address added: 3
  B0:26:28:7F:F5:C1
  B0:26:28:7F:22:33
  B0:26:28:7F:22:34
testpmd>
testpmd> mac_addr remove 0 B0:26:28:7F:22:33
testpmd> show port 0 macs
Number of MAC address added: 2
  B0:26:28:7F:F5:C1
  B0:26:28:7F:22:34

Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>