nb/intel/{gm45,i945,pineview}: Use macro instead of GGC address

Change-Id: I233e835180fd445961b6deb74ea7afc2821c236e
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/28909
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/src/northbridge/intel/i945/early_init.c b/src/northbridge/intel/i945/early_init.c
index 7de2c73..a38874a 100644
--- a/src/northbridge/intel/i945/early_init.c
+++ b/src/northbridge/intel/i945/early_init.c
@@ -685,7 +685,7 @@
 	if (reg32 == 0x030000) {
 		printk(BIOS_DEBUG, "PCIe device is VGA. Disabling IGD.\n");
 		reg16 = (1 << 1);
-		pci_write_config16(PCI_DEV(0, 0x0, 0), 0x52, reg16);
+		pci_write_config16(PCI_DEV(0, 0x0, 0), GGC, reg16);
 
 		reg32 = pci_read_config32(PCI_DEV(0, 0x0, 0), DEVEN);
 		reg32 &= ~(DEVEN_D2F0 | DEVEN_D2F1);