northbridge/via: Use DEVICE_NOOP macro over dummy symbol

Change-Id: Ib9d0fae363c5c1fbed3a63cb8aa86716cf1f9ee1
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/7289
Tested-by: build bot (Jenkins)
Reviewed-by: Bruce Griffith <Bruce.Griffith@se-eng.com>
14 files changed