fix the computation of etaZ, the meaning of SEAICEetaZmethod was flipped (2<->1)
fix the computation of etaZ, the meaning of SEAICEetaZmethod was
flipped (2<->1)

altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h