net/mlx5: Modify struct mlx5_irq to use struct msi_map

Use the standard struct msi_map to store the vector number and irq
number pair in struct mlx5_irq.

Signed-off-by: Eli Cohen <elic@nvidia.com>
Reviewed-by: Shay Drory <shayd@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>