e1000: add dropped DMA receive enable back in for WoL

Commit d5bc77a2 broke Wake-on-LAN by
inadvertently dropping the enabling of DMA receives.

Restore the enabling of DMA receives for WoL.

This is applicable to 3.1+ stable trees.

CC: stable@vger.stable.org
Reported-by: Tobias Klausmann <klausman@schwarzvogel.de>
Signed-off-by: Dean Nelson <dnelson@redhat.com>
Tested-by: Tobias Klausmann <klausman@schwarzvogel.de>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>