run: split netperf l4linux script

Split the netperf run script into 3 ones so that it can be used more easily
in an automated run.

It is solely for foc_arndale by now.

l4linux_netperf.run        - use nic via usb2.0
l4linux_netperf-usb30.run  - use nic via usb3.0
l4linux_netperf-bridge.run - use nic via usb3.0 + bridge
add netperf tests to autopilot list
run: prepare netperf l4lx output for post processing