net/mlx5: fix unlimited parsing of switch info

net/mlx5: fix unlimited parsing of switch info

In mlx5_sysfs_switch_info function, the driver gets switch information
associated with network interface.

The driver writes the port name into buffer and translates it.
However, when it writes the name, it does not limit writing to the
buffer size.

Limit writing to the size of the buffer.

Fixes: 1256805dd54d ("net/mlx5: move Linux-specific functions")
Cc: stable@dpdk.org
Signed-off-by: Michael Baum <michaelba@mellanox.com>
Acked-by: Matan Azrad <matan@mellanox.com>