PCI: fix nit in ROM BAR size probing

When probing for ROM BAR size, we should not change bits 1:10 in this
BAR, because these bits are marked as "reserved for future use" in PCI
spec, so changing them might have side effects.

No such issue for I/O or memory, as there is an implementation note in
PCI spec which explicitly allows writing 0xfffffffff there.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/probe.c

@@ -165,12 +165,12 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 {
 	u32 l, sz, mask;
 
-	mask = type ? ~PCI_ROM_ADDRESS_ENABLE : ~0;
+	mask = type ? PCI_ROM_ADDRESS_MASK : ~0;
 
 	res->name = pci_name(dev);
 
 	pci_read_config_dword(dev, pos, &l);
-	pci_write_config_dword(dev, pos, mask);
+	pci_write_config_dword(dev, pos, l | mask);
 	pci_read_config_dword(dev, pos, &sz);
 	pci_write_config_dword(dev, pos, l);