net/mlx5e: Consider aggregated port speed during rate configuration

When LAG is configured, functions (PF,VF,SF) can utilize the maximum
aggregated link speed for transmission. Currently the aggregated link
speed is not considered.

Hence, improve it to use the aggregated link speed by referring to the
physical port's upper bonding device when LAG is configured.

Signed-off-by: Jianbo Liu <jianbol@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>