RELOCATABLE_RAMSTAGE: Fix weak symbols with option ROMs

After relocation the weak symbol map_oprom_vendev is no longer NULL.
Always have empty stub function defined.

Change-Id: I5b1bdeb3f37bb04363cf3d9dedaeafc9e193aaae
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/7956
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
2 files changed