aopen/dxplplusu,intel/e7505: Move mainboard_romstage_entry()

Change-Id: I15aaefdf0c81f58adfeb6f4dde2f05b3c06fd145
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38266
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/northbridge/intel/e7505/Makefile.inc

@@ -3,6 +3,7 @@ ifeq ($(CONFIG_NORTHBRIDGE_INTEL_E7505),y)
 ramstage-y += northbridge.c
 ramstage-y += memmap.c
 
+romstage-y += romstage.c
 romstage-y += raminit.c
 romstage-y += memmap.c