Restructured PCI subsystem to fit the new device model.

Generic PCI code now handles 64-bit BARs correctly when setting
"membase"; drivers should need to call pci_bar_start() only if they want
to use BARs other than the first memory or I/O BAR.

Split rarely-used PCI functions out into pciextra.c.

Core PCI code is now 662 bytes (down from 1308 bytes in Etherboot 5.4).
284 bytes of this saving comes from the pci/pciextra split.

Cosmetic changes to lots of drivers (e.g. vendor_id->vendor in order to
match the names used in Linux).

src/arch/i386/prefix/select_pci.c

@@ -1,28 +0,0 @@
-#include "dev.h"
-#include <gpxe/pci.h>
-#include "registers.h"
-
-/*
- * Register a device as the default PCI boot device.  This code is
- * called by the PCI ROM prefix.
- *
- * Do not move this code to drivers/bus/pci.c, because it is
- * i386-specific, and don't merge it with select_isapnp.c, because
- * that would cause linker symbol pollution.
- *
- */
-void i386_select_pci_device ( struct i386_all_regs *ix86 ) {
-	/*
-	 * PCI BIOS passes busdevfn in %ax
-	 *
-	 */
-	union {
-		struct bus_loc bus_loc;
-		struct pci_loc pci_loc;
-	} u;
-	
-	/* Select PCI bus and specified busdevfn as first boot device */
-	memset ( &u, 0, sizeof ( u ) );
-	u.pci_loc.busdevfn = ix86->regs.ax;
-	select_device ( &dev, &pci_driver, &u.bus_loc );
-}