This commit adds an e1000e driver based on Intel source code
available at:

    http://sourceforge.net/projects/e1000/

which is upstream source for the Linux kernel e1000 drivers, and
should support many PCIe e1000 variants.

Signed-off-by: Marty Connor <mdc@etherboot.org>

This commit replaces the current gPXE e1000 driver with one ported
from Intel source code available at

    http://sourceforge.net/projects/e1000/

which is upstream source for the Linux kernel e1000 drivers, and
should support most if not all PCI e1000 variants.

Signed-off-by: Marty Connor <mdc@etherboot.org>