ports-foc: Enable l4inux_netperf tests for x86

USB network cards can now be tested on x86.

Ref #1143
usb_drv: Check SCSI command queue state

In case the storage-entry point dispatches more then one packet, wait for the
previous command to finish before setting a new request. This has to be done
because the 'queuecommand' does actually *not* queue things, but can only handle
one request at the time.

Fix #1143