e1000: remove obsolete custom pci_save_state code

Now that 2.6.19 provides a proper implementation that saves MSI, PCI-E
config space, we can have the e1000 driver use those instead of it's
custom implementation.

Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>