e1000: add dropped DMA receive enable back in for WoL

commit b868179c47e9e8eadcd04c1f3105998e528988a3 upstream.

Commit d5bc77a223b0e9b9dfb002048d2b34a79e7d0b48 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.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>