net/mlx5: FPGA, Properly initialize dma direction on fpga conn send

Properly initialize dma direction on fpga conn send.
Do not rely on dma_dir == 0 (DMA_BIDIRECTIONAL).

Signed-off-by: Ilya Lesokhin <ilyal@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>