net/mlx5: E-switch, Respect BW share of the new group

To enable transmit schduler on vport FW require non-zero configuration
for vport's TSAR. If vport added to the group which has configured BW
share value and TX rate values of the vport are zero, then scheduler
wouldn't be enabled on this vport.
Fix that by calling BW normalization if BW share of the new group is
configured.

Fixes: 0fe132ea ("net/mlx5: E-switch, Allow to add vports to rate groups")
Signed-off-by: Dmytro Linkin <dlinkin@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>