net/mlx5: DR: Fix incorrect type in argument

HW spec objects should receive a void ptr to work on, the MLX5_SET/GET
macro will know how to handle it.

No need to provide explicit or wrong pointer type in this case.

warning: incorrect type in argument 1 (different base types)
    expected unsigned long long const [usertype] *sw_action
    got restricted __be64 [usertype] *[assigned] sw_action

Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>