superio/smsc/smscsuperio: Make romstage linkable with header

Rewrite smsc/smscsuperio romstage component to be more consistent and
provide header there-by removing #include's of early_serial.c's in
mainboard's.

Change-Id: I572e0c76422f09d4de88935a36c0a59e5350e6e0
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/5915
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
diff --git a/src/mainboard/intel/d810e2cb/romstage.c b/src/mainboard/intel/d810e2cb/romstage.c
index 4394377..6c277d5 100644
--- a/src/mainboard/intel/d810e2cb/romstage.c
+++ b/src/mainboard/intel/d810e2cb/romstage.c
@@ -29,7 +29,7 @@
 #include "northbridge/intel/i82810/raminit.h"
 #include "drivers/pc80/udelay_io.c"
 #include "cpu/x86/bist.h"
-#include "superio/smsc/smscsuperio/early_serial.c"
+#include <superio/smsc/smscsuperio/smscsuperio.h>
 #include "gpio.c"
 #include <lib.h>