net/mlx5: DR, Fix missing flow_source when creating multi-destination FW table

In order to support multiple destination FTEs with SW steering
FW table is created with single FTE with multiple actions and
SW steering rule forward to it. When creating this table, flow
source isn't set according to the original FTE.

Fix this by passing the original FTE flow source to the created
FW table.

Fixes: 34583bee ("net/mlx5: DR, Create multi-destination table for SW-steering use")
Signed-off-by: Maor Dickman <maord@nvidia.com>
Reviewed-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>