ethernet/eth_e1000.c: change to new PCI(e) functions

Migrate from "legacy" PCI support (drivers/pci) to new PCI(e) support.

The e1000 driver is merely for testing with QEMU and so should not be
a model for the use of PCI(e) functions. Consult instead "real-world"
PCI(e) drivers like the NS16550 UART (drivers/serial/uart_ns16550.c).

Signed-off-by: Charles Youse <charles.youse@intel.com>