Move select MMCONF_SUPPORT under northbridge (fix)

I missed the board with gm45 when I moved MMCONF_SUPPORT lines.

Also, the intel/i3100 does not have MMCONF_SUPPORT implemented
even though it was previously selected for intel/eagleheights board.

Change-Id: I9c7f6b0a150b4d54288a1e015277b9d98467fca4
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/3598
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
diff --git a/src/northbridge/intel/gm45/Kconfig b/src/northbridge/intel/gm45/Kconfig
index 34b2544..16a0bf1 100644
--- a/src/northbridge/intel/gm45/Kconfig
+++ b/src/northbridge/intel/gm45/Kconfig
@@ -25,6 +25,7 @@
 config NORTHBRIDGE_SPECIFIC_OPTIONS # dummy
 	def_bool y
 	select HAVE_DEBUG_RAM_SETUP
+	select MMCONF_SUPPORT
 	select MMCONF_SUPPORT_DEFAULT
 	select IOMMU