intel.lua: Added selftest_tso() test case for TCP Segmentation Offload.

Just a failing test for now because TSO is not yet implemented.

Progress on issue #33.
Fixed register address offset for ICR.
Merge pull request #36 from pkazmier/master

Looks like a small typo in one of the register address offsets.
Merge branch 'master' into issue33

merge sample test case given by @lukego and register fix
intel.lua: removed invalid ethernet frame start check; fixing offsets based on packet data