igb: Fix extts capture value format for 82580/i354/i350

igb: Fix extts capture value format for 82580/i354/i350

82580/i354/i350 features circle-counter-like timestamp registers
that are different with newer i210. The EXTTS capture value in
AUXTSMPx should be converted from raw circle counter value to
timestamp value in resolution of 1 nanosec by the driver.

This issue can be reproduced on i350 nics, connecting an 1PPS
signal to a SDP pin, and run 'ts2phc' command to read external
1PPS timestamp value. On i210 this works fine, but on i350 the
extts is not correctly converted.

The i350/i354/82580's SYSTIM and other timestamp registers are
40bit counters, presenting time range of 2^40 ns, that means these
registers overflows every about 1099s. This causes all these regs
can't be used directly in contrast to the newer i210/i211s.

The igb driver needs to convert these raw register values to
valid time stamp format by using kernel timecounter apis for i350s
families. Here the igb_extts() just forgot to do the convert.

Fixes: 38970eac41db ("igb: support EXTTS on 82580/i354/i350")
Signed-off-by: Yuezhen Luan <eggcar.luan@gmail.com>
Reviewed-by: Jacob Keller <jacob.e.keller@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>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230607164116.3768175-1-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>