Use TRex release v2.41 to support both x86 and aarch64

Use TRex release v2.41 to support both x86 and aarch64

Currently Yardstick uses Cisco's TRex release v2.28 which
can only support x86, for the consideration of
multi-arch support of Yardstick, the trex release v2.41
is now available and it can support multi-arch(both x86
and aarch64) now.

For the external lib of v2.41, for x86_64, it looks like:
external_libs/pyzmq-14.5.0/python2/intel/ucs4/64bit/zmq
for arm64, it looks like:
external_libs/pyzmq-14.5.0/python2/arm/ucs4/64bit/zmq
So replace the trex release v2.28 with v2.41.

JIRA: YARDSTICK-1191

Change-Id: I22dc3499283d48a89da1145cc480fd7d2a93a1cc
Signed-off-by: trevortao <trevor.tao@arm.com>
(cherry picked from commit 13f19d35a04ffb46ca673e81385779bc46c48781)