net/mlx5e: E-Switch, Add PTP counters for uplink representor

There is a configuration where the uplink interface is the synchronizer.
Add PTP counters for this interface for monitoring.

Signed-off-by: Aya Levin <ayal@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>