[x86_64] Fix assorted 64-bit compilation errors and warnings

Remove various 32-bit assumptions scattered throughout the codebase.
The code is still not necessarily 64-bit clean, but will at least
compile.

src/drivers/net/prism2_plx.c

@@ -48,7 +48,6 @@ static int prism2_find_plx ( hfa384x_t *hw, struct pci_device *p )
   iobase &= PCI_BASE_ADDRESS_IO_MASK;
 
   /* Fill out hw structure */
-  hw->membase = attr_mem;
   hw->iobase = iobase;
   printf ( "PLX9052 has local config registers at %#x\n", plx_lcr );
   printf ( "Prism2 has attribute memory at %#x and I/O base at %#x\n", attr_mem, iobase );