The tstamp_config structure is being set inside of
ice_ptp_cfg_timestamp, which is the function used to set Tx and
Rx timestamping during initialization.

This function is also used in order to set the PHY port timestamping
status. However, it makes sense to always set the tstamp_config directly
whenever the ice_set_tx_tstamp or ice_set_rx_tstamp functions are
called.

Move assignment of tstamp_config into the related functions and out of
ice_ptp_cfg_timestamp.

Now that we assign the timestamp mode in the relevant functions, we no
longer modify the config value in ice_set_timestamp_mode. In turn, we
no longer want to copy that config value into the PF cached structure.
Instead, this is now the source of truth for actual configuration. On
success of ice_set_timestamp_mode, copy the real configured mode back to
report it out to userspace.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>