e1000e: workaround for packet drop on 82579 at 100Mbps

The MAC can drop short packets when the PHY detects noise on the line at
100Mbps due to a timing issue.  Workaround the issue by increasing the PLL
counter so the PHY properly recognizes the synchronization pattern from the
MAC.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>