SMM: Only have console with DEBUG_SMI

Existing code compiled serial communication and printk() for SMM
even when DEBUG_SMI was not selected.

Change-Id: Ic5e25cd7453cb2243f7ac592b093fba752a299f7
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/5142
Tested-by: build bot (Jenkins)
Reviewed-by: Vladimir Serbinenko <phcoder@gmail.com>
diff --git a/src/drivers/uart/Makefile.inc b/src/drivers/uart/Makefile.inc
index 3a9ca3d..415c5bb 100644
--- a/src/drivers/uart/Makefile.inc
+++ b/src/drivers/uart/Makefile.inc
@@ -2,19 +2,19 @@
 romstage-y += util.c
 ramstage-y += util.c
 bootblock-y += util.c
-smm-y += util.c
+smm-$(CONFIG_DEBUG_SMI) += util.c
 endif
 
 ifeq ($(CONFIG_CONSOLE_SERIAL8250),y)
 romstage-y += uart8250io.c
 ramstage-y += uart8250io.c
-smm-y += uart8250io.c
+smm-$(CONFIG_DEBUG_SMI) += uart8250io.c
 endif
 
 ifeq ($(CONFIG_CONSOLE_SERIAL8250MEM),y)
 romstage-y += uart8250mem.c
 ramstage-y += uart8250mem.c
-smm-y += uart8250mem.c
+smm-$(CONFIG_DEBUG_SMI) += uart8250mem.c
 endif
 
 ifeq ($(CONFIG_CONSOLE_SERIAL_UART),y)