i40e: Delete unused and useless i40e_pf fields

i40e: Delete unused and useless i40e_pf fields

Removed fields:
.fc_autoneg_status
    Since commit c56999f94876 ("i40e/i40evf: Add set_fc and init of
    FC settings") write-only and otherwise unused
.eeprom_version
    Write-only and otherwise unused
.atr_sample_rate
    Has only one possible value (I40E_DEFAULT_ATR_SAMPLE_RATE). Remove
    it and replace its occurrences by I40E_DEFAULT_ATR_SAMPLE_RATE
.adminq_work_limit
    Has only one possible value (I40E_AQ_WORK_LIMIT). Remove it and
    replace its occurrences by I40E_AQ_WORK_LIMIT
.tx_sluggish_count
    Unused, never written
.pf_seid
    Used to store VSI downlink seid and it is referenced only once
    in the same codepath. There is no need to save it into i40e_pf.
    Remove it and use downlink_seid directly in the mentioned log
    message.
.instance
    Write only. Remove it as well as ugly static local variable
    'pfs_found' in i40e_probe.
.int_policy
.switch_kobj
.ptp_pps_work
.ptp_extts1_work
.ptp_pps_start
.pps_delay
.ptp_pin
.override_q_count
    All these unused at all

Prior the patch:
pahole -Ci40e_pf drivers/net/ethernet/intel/i40e/i40e.ko | tail -5
        /* size: 5368, cachelines: 84, members: 127 */
        /* sum members: 5297, holes: 20, sum holes: 71 */
        /* paddings: 6, sum paddings: 19 */
        /* last cacheline: 56 bytes */
};

After the patch:
pahole -Ci40e_pf drivers/net/ethernet/intel/i40e/i40e.ko | tail -5
        /* size: 4976, cachelines: 78, members: 112 */
        /* sum members: 4905, holes: 17, sum holes: 71 */
        /* paddings: 6, sum paddings: 19 */
        /* last cacheline: 48 bytes */
};

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>