net/mlx5: Use dev->priv.name instead of dev_name

Use mlx5_core mdev private name in message instead of using pci dev_name
to provide a better report/debug of different mlx5 device types.

This patch does not change any functionality.

Signed-off-by: Huy Nguyen <huyn@mellanox.com>
Signed-off-by: Vu Pham <vuhuong@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>