net/mlx5: clean-up developer logs

net/mlx5: clean-up developer logs

Split maintainers logs from user logs.

A lot of debug logs are present providing internal information on how
the PMD works to users.  Such logs should not be available for them and
thus should remain available only when the PMD is compiled in debug
mode.

This commits removes some useless debug logs, move the Maintainers ones
under DEBUG and also move dump into debug mode only.

Cc: stable@dpdk.org
Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>