net/mlx5: Bridge, provide flow source hints

Currently, SMFS mode doesn't support rx-loopback flows which causes bridge
egress rules to be rejected because without hint rules for both rx and tx
destinations are created by default. Provide explicit flow source hints for
compatibility with SMFS.

Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>