meta-webos-backports: Add iftop recipe for network monitoring

- The iftop is a network monitoring tool

[GF-4197] Integrate tools to measure network performance for wired/wireless connection

Open-webOS-DCO-1.0-Signed-off-by: Sangwoo Kang <sangwoo82.kang@lge.com>

Change-Id: If846824c2c94f32822e2408d8d213da36c83e33b
Reviewed-on: https://g2g.palm.com/2061
Reviewed-by: Lokesh Kumar Goel <lokeshkumar.goel@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Sangwoo Kang <sangwoo82.kang@lge.com>
Tested-by: Sangwoo Kang <sangwoo82.kang@lge.com>
Reviewed-by: Iyad Qumei <iyad.qumei@palm.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>