mana: TX SGE0 and WQE for LSO should meet GDMA requirements

GDMA requires that SGE0 for the LSO TX WQE should:

- Only contain the header
- Should not exceed 256 bytes
- There should be > 1 SGL in the TX LSO WQE

Also added:
- Test cases to cover the above requirements
- Test configuration hook

Author: sunilmut