ixgbe: fix WOL register setup for 82599

We need to have the WUS register set to all 1's in order for the hardware
to be capable of ever waking up.  Set it here in the ixgbe_probe().

Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>