Move global io_base_addr into compilation units

Corresponding to flashrom svn r1813.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
diff --git a/gfxnvidia.c b/gfxnvidia.c
index d3ee14e..2a5c7ae 100644
--- a/gfxnvidia.c
+++ b/gfxnvidia.c
@@ -89,7 +89,7 @@
 	if (!dev)
 		return 1;
 
-	io_base_addr = pcidev_readbar(dev, PCI_BASE_ADDRESS_0);
+	uint32_t io_base_addr = pcidev_readbar(dev, PCI_BASE_ADDRESS_0);
 	if (!io_base_addr)
 		return 1;