nb/intel/gm45: Define and use MMCONF_BUS_NUMBER

Change-Id: I635f3615f566502f79bbd81f9f743ce63bba3b1a
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49758
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/northbridge/intel/gm45/Kconfig b/src/northbridge/intel/gm45/Kconfig
index 4637a22..256b088 100644
--- a/src/northbridge/intel/gm45/Kconfig
+++ b/src/northbridge/intel/gm45/Kconfig
@@ -29,6 +29,10 @@
 config MMCONF_BASE_ADDRESS
 	default 0xf0000000
 
+config MMCONF_BUS_NUMBER
+	int
+	default 64
+
 config SMM_RESERVED_SIZE
 	hex
 	default 0x100000