nb/i945/raminit.c: Use Makefile.inc instead of '#include rcven.c'

Change-Id: Ib86600b687c7002646ca82d5fa52121b6eafcd60
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/18087
Tested-by: build bot (Jenkins)
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
diff --git a/src/northbridge/intel/i945/Makefile.inc b/src/northbridge/intel/i945/Makefile.inc
index 6b176c2..0e4fcfc 100644
--- a/src/northbridge/intel/i945/Makefile.inc
+++ b/src/northbridge/intel/i945/Makefile.inc
@@ -25,6 +25,7 @@
 romstage-y += early_init.c
 romstage-y += errata.c
 romstage-y += debug.c
+romstage-y += rcven.c
 
 smm-y += udelay.c