nb/intel/i945: Move boilerplate romstage to a common location

This adds callbacks for mainboard specific init.

Change-Id: Ib67bc492a7b7f02f9b57a52fd6730e16501b436e
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36787
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/northbridge/intel/i945/Makefile.inc b/src/northbridge/intel/i945/Makefile.inc
index af3c235..585d61b 100644
--- a/src/northbridge/intel/i945/Makefile.inc
+++ b/src/northbridge/intel/i945/Makefile.inc
@@ -20,6 +20,7 @@
 ramstage-y += gma.c
 ramstage-y += acpi.c
 
+romstage-y += romstage.c
 romstage-y += memmap.c
 romstage-y += raminit.c
 romstage-y += early_init.c