net/mlx5: Consolidate flow rules regardless their flow tag

Flow rules with same match criteria and value should be mapped to
the same flow table entry regardless the flow tag identifier.

Flow tag is part of flow table entry context and not of the
destination, therefore we should return error when we try to add
destination to flow table entry with different flow tag.

Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>