igb: Remove incorrect "unexpected SYS WRAP" log message

TSAUXC.DisableSystime is never set, so SYSTIM runs into a SYS WRAP
every 1100 secs on 80580/i350/i354 (40 bit SYSTIM) and every 35000
secs on 80576 (45 bit SYSTIM).

This wrap event sets the TSICR.SysWrap bit unconditionally.

However, checking TSIM at interrupt time shows that this event does not
actually cause the interrupt.  Rather, it's just bycatch while the
actual interrupt is caused by, for instance, TSICR.TXTS.

The conclusion is that the SYS WRAP is actually expected, so the
"unexpected SYS WRAP" message is entirely bogus and just helps to
confuse users.  Drop it.

Signed-off-by: Corinna Vinschen <vinschen@redhat.com>
Acked-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>