net/mlx5: Avoid shadowing numa_node

Avoid using a local variable named numa_node to avoid shadowing a public
one.

Fixes: db058a18 ('net/mlx5_core: Set irq affinity hints')
Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>