net/mlx5_core: Fix min vectors value in mlx5_enable_msix

mlx5 requires at least one interrupt vector for completions so fix the minvec
argument to pci_enable_msix_range() accordingly.

Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>