Updated armband

Project: yardstick  5d0fb5e5ed3fc324cac995994b061b6d449fc869

[Yardstick-233]latency measurment by using pktgen-dpdk

VM A runs pktgen-dpdk as a traffic generator and is connected
back-to-back with VM B running testpmd for forwarding packets.

1. use linux expect to fetch the latency statics data.
2. fetch 10 samples of latency and calculate avg_latency.
3. use screen to keep test scripts running in the background.
4. add a function send_command() for screen in ssh.py

JIRA:YARDSTICK-233

Change-Id: I90ae64b3d198c79f159275ae35715eb284f05080
Signed-off-by: wu.zhihui <wu.zhihui1@zte.com.cn>

diff --git a/upstream/yardstick b/upstream/yardstick
index 3f9d76e..5d0fb5e 160000 (submodule)
--- a/upstream/yardstick
+++ b/upstream/yardstick
@@ -1 +1 @@
-Subproject commit 3f9d76ec447d917446fd4dd3dd8c0a2a3f758f33
+Subproject commit 5d0fb5e5ed3fc324cac995994b061b6d449fc869