net/mlx5e: Fix ingress rate configuration for representors

Current code uses the old method of prio encoding in
flow_cls_common_offload. Fix to follow the changes introduced in
commit ef01adae ("net: sched: use major priority number as hardware priority").

Fixes: fcb64c0f ("net/mlx5: E-Switch, add ingress rate support")
Signed-off-by: Eli Cohen <eli@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>