net/mlx5: Add creation flags when adding new flow table

When creating flow tables, allow the caller to specify creation flags.
Currently no flags are used and as such this patch doesn't add any new
functionality.

Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>