net/mlx5: enable debug logs dynamically

net/mlx5: enable debug logs dynamically

Most debug logs are using DRV_LOG(DEBUG,)
but some were using DEBUG().
The macro DEBUG is doing nothing if not compiled with
RTE_LIBRTE_MLX5_DEBUG.

As it is not used in the data path, the macro DEBUG
can be replaced with DRV_LOG.
Then all debug logs can be enabled at runtime with:
	--log-level pmd.net.mlx5:debug

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Matan Azrad <matan@nvidia.com>