verstage: provide support for serial console

verstage previously lacked serial console support.
Add the necessary objects and macro checks to allow
verstage to include the serial console.

Change-Id: Ibe911ad347cac0b089f5bc0d4263956f44f3d116
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/10196
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins)

src/drivers/uart/Makefile.inc

@@ -4,6 +4,7 @@ romstage-y += util.c
 ramstage-y += util.c
 bootblock-y += util.c
 secmon-y += util.c
+verstage-y += util.c
 smm-$(CONFIG_DEBUG_SMI) += util.c
 
 # Add the driver, only one can be enabled. The driver files may