intel/i945: Use define for `BSM`

Change-Id: Ia58d8b410a145f27f0b267c115714580c366e063
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/5929
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins)
diff --git a/src/northbridge/intel/i945/early_init.c b/src/northbridge/intel/i945/early_init.c
index b12ad3a..0b2acd7 100644
--- a/src/northbridge/intel/i945/early_init.c
+++ b/src/northbridge/intel/i945/early_init.c
@@ -943,7 +943,7 @@
 
 	{
 		/* This will not work if TSEG is in place! */
-		u32 tom = pci_read_config32(PCI_DEV(0, 2, 0), 0x5c);
+		u32 tom = pci_read_config32(PCI_DEV(0, 2, 0), BSM);
 
 		printk(BIOS_DEBUG, "TOM: 0x%08x\n", tom);
 		ram_check(0x00000000, 0x000a0000);