igb: Workaround for i210 Errata 25: Slow System Clock

igb: Workaround for i210 Errata 25: Slow System Clock

commit 948264879b6894dc389a44b99fae4f0b72932619 upstream.

On some devices, the internal PLL circuit occasionally provides the
wrong clock frequency after power up. The probability of failure is less
than one failure per 1000 power cycles. When the failure occurs, the
internal clock frequency is around 1/20 of the correct frequency.

Signed-off-by: Todd Fujinaka <todd.fujinaka@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>