net/mlx5: Query maximum frequency adjustment of the PTP hardware clock

Some mlx5 devices do not support the default advertised maximum frequency
adjustment value for the PTP hardware clock that is set by the driver.
These devices need to be queried when initializing the clock functionality
in order to get the maximum supported frequency adjustment value. This
value can be greater than the minimum supported frequency adjustment across
mlx5 devices (50 million ppb).

Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>