vboot2: implement select_firmware for pre-romstage verification

This patch has a basic structure of vboot2 integration. It supports only Nyans,
which have bootblock architecture and romstage architecture are
compatible from linker's perspective.

TEST=Built with VBOOT2_VERIFY_FIRMWARE on/off. Booted Nyan Blaze.
BUG=None
BRANCH=none
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>

Change-Id: I4bbd4d0452604943b376bef20ea8a258820810aa
Reviewed-on: https://chromium-review.googlesource.com/204522
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
Commit-Queue: Daisuke Nojiri <dnojiri@chromium.org>
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>

src/console/Makefile.inc

@@ -9,6 +9,10 @@ smm-y += printk.c
 smm-y += vtxprintf.c
 smm-$(CONFIG_SMM_TSEG) += die.c
 
+verstage-$(CONFIG_EARLY_CONSOLE) += vtxprintf.c
+verstage-y += console.c
+verstage-y += die.c
+
 romstage-$(CONFIG_EARLY_CONSOLE) += vtxprintf.c
 romstage-y += console.c
 romstage-y += post.c

src/console/console.c

@@ -126,6 +126,8 @@ void console_init(void)
 		COREBOOT_EXTRA_VERSION
 #if defined(__BOOT_BLOCK__)
 		" bootblock "
+#elif defined(__VER_STAGE__)
+		" verstage "
 #else
 		" romstage "
 #endif