ixgbevf: Link lost in VM on ixgbevf when restoring from freeze or suspend

This patch fixed issue in VM which shows no link when hypervisor is
restored from low-power state. The driver is responsible for re-enabling
any features of the device that had been disabled during suspend calls,
such as IRQs and bus mastering.

Signed-off-by: Radoslaw Tyl <radoslawx.tyl@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>