Back out the TSO support diff, since we got issues reported for which

Back out the TSO support diff, since we got issues reported for which
no solution could be found.  Known issues at this point:

1. sparc64 panics, probably because of an alignment issue in struct
   tcphdr { th_off }.  A diff for potentially fixing the alignment issue
   exists, but testing is pending.
2. Watchdogs reported on the I350 chip, which can't be reproduced on own
   hardware.