net/mlx4_core: Configure mlx4 hardware for mixed RoCE v1/v2 modes

If the hardware supports RoCE v2 (mixed with RoCE v1) mode, we enable
it. This is necessary in order to support RoCE v2.

Signed-off-by: Moni Shoua <monis@mellanox.com>
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>