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/nicrealtek.c b/nicrealtek.c
index 02fbd39..4a440ea 100644
--- a/nicrealtek.c
+++ b/nicrealtek.c
@@ -28,6 +28,7 @@
 #define PCI_VENDOR_ID_REALTEK	0x10ec
 #define PCI_VENDOR_ID_SMC1211	0x1113
 
+static uint32_t io_base_addr = 0;
 static int bios_rom_addr, bios_rom_data;
 
 const struct dev_entry nics_realtek[] = {