net/mlx5: Move affinity assignment into irq_request

Move affinity binding of the IRQ to irq_request function in order to
bind the IRQ before inserting it to the xarray.

After this change, the IRQ is ready for use when inserted to the xarray.

Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>