net/mlx5: consolidate condition checks for TSO
net/mlx5: consolidate condition checks for TSO

This change helps compiler to better optimize the code.

Signed-off-by: Yongseok Koh <76b37c91816d73ef9cf709e3e83a68f2d162f1e2@mellanox.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk