Move general TSO declarations in a separate header to be able to use
them in other datapaths (not only EFX). Also update the function that
prepares TSO header to make it useful in other datapaths.
Signed-off-by: Igor Romanov <igor.romanov@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>