e100: adapt to the reworked PCI PM

Adapt the e100 driver to the reworked PCI PM

* Use the observation that it is sufficient to call pci_enable_wake()
  once, unless it fails

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Tested-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Frans Pop <elendil@planet.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>