nb/intel/i440bx: Switch to POSTCAR_STAGE

Boot tested on asus/p2b-ls and p2b-ds.

Change-Id: I0154f1d120bef3b45286fb4314f0de419cd8341e
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Signed-off-by: Keith Hui <buurin@gmail.com>
Reviewed-on: https://review.coreboot.org/26821
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/northbridge/intel/i440bx/Makefile.inc b/src/northbridge/intel/i440bx/Makefile.inc
index b0ca180..d41f65d 100644
--- a/src/northbridge/intel/i440bx/Makefile.inc
+++ b/src/northbridge/intel/i440bx/Makefile.inc
@@ -23,4 +23,6 @@
 romstage-$(CONFIG_DEBUG_RAM_SETUP) += debug.c
 romstage-y += ram_calc.c
 
+postcar-y += ram_calc.c
+
 endif