x86: Use CONFIG_SERIAL_MULTI

Signed-off-by: Graeme Russ <graeme.russ@gmail.com>
diff --git a/common/serial.c b/common/serial.c
index 0682faa..fceabfa 100644
--- a/common/serial.c
+++ b/common/serial.c
@@ -41,7 +41,8 @@
 #elif defined(CONFIG_405GP) || defined(CONFIG_405CR) || defined(CONFIG_440) \
    || defined(CONFIG_405EP) || defined(CONFIG_405EZ) || defined(CONFIG_405EX) \
    || defined(CONFIG_MPC5xxx) || defined(CONFIG_MPC83xx) \
-   || defined(CONFIG_MPC85xx) || defined(CONFIG_MPC86xx)
+   || defined(CONFIG_MPC85xx) || defined(CONFIG_MPC86xx) \
+   || defined(CONFIG_SYS_SC520)
 #if defined(CONFIG_CONS_INDEX) && defined(CONFIG_SYS_NS16550_SERIAL)
 #if (CONFIG_CONS_INDEX==1)
 	return &eserial1_device;