net/mlx5: add log file procedure for debug data

Add a global function in the PMD which dumps debug information to
specific file.

The data can be printed in hexadecimal format or as regular string.

The number of debug files per PMD entity should be limited by a new PMD
probe parameter called max_dump_files_num.

The files will be created in the /var/log directory or in the current
directory.

Cc: stable@dpdk.org
Signed-off-by: Matan Azrad <matan@mellanox.com>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>