Hack: Move pci BAR ranges.

The Linux kernel will re-allocate all of these, tickling what appears
to be a bug in QEMU.  Work around this by moving the ranges allocated
by the console so that the new ranges don't overlap.
diff --git a/pci.c b/pci.c
index 45739ff..87a101c 100644
--- a/pci.c
+++ b/pci.c
@@ -141,8 +141,8 @@
 void
 pci_setup(void)
 {
-  uint32_t io_base = 0x8000;
-  uint32_t mem_base = (128+16) * 1024 * 1024;
+  uint32_t io_base = 0xc000;
+  uint32_t mem_base = 256 * 1024 * 1024;
   int bdf, max;
 
   foreachpci (bdf, max)