net/mlx5: Use the correct IPsec capability function for FPGA ops

Currently the IPsec acceleration capability function is also used
at IPsec fpga capable device code.

This could cause a future bug as the acceleration layer is agnostic
to the device implementing its API.

Fix by using the IPsec FPGA capability function instead of acceleration
layer capability function in case of FPGA IPsec only related operations.

Downstream patches will add support for Connect-X IPsec, this can avoid
a future bug.

Signed-off-by: Raed Salem <raeds@mellanox.com>
Reviewed-by: Boris Pismenny <borisp@mellanox.com>
Reviewed-by: Huy Nguyen <huyn@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>