common/mlx5: introduce common library

common/mlx5: introduce common library

A new Mellanox vdpa PMD will be added to support vdpa operations by
Mellanox adapters.

This vdpa PMD design includes mlx5_glue and mlx5_devx operations and
large parts of them are shared with the net/mlx5 PMD.

Create a new common library in drivers/common for mlx5 PMDs.
Move mlx5_glue, mlx5_devx_cmds and their dependencies to the new mlx5
common library in drivers/common.

The files mlx5_devx_cmds.c, mlx5_devx_cmds.h, mlx5_glue.c,
mlx5_glue.h and mlx5_prm.h are moved as is from drivers/net/mlx5 to
drivers/common/mlx5.

Share the log mechanism macros.
Separate also the log mechanism to allow different log level control to
the common library.

Build files and version files are adjusted accordingly.
Include lines are adjusted accordingly.

Signed-off-by: Matan Azrad <matan@mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>