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>

src/console/Makefile.inc

@@ -5,8 +5,7 @@ ramstage-y += vsprintf.c
 ramstage-y += post.c
 ramstage-y += die.c
 
-smm-y += printk.c
-smm-y += vtxprintf.c
+smm-$(CONFIG_DEBUG_SMI) += vtxprintf.c printk.c
 smm-$(CONFIG_SMM_TSEG) += die.c
 
 romstage-$(CONFIG_EARLY_CONSOLE) += vtxprintf.c