vboot: provide a unified flow for separate verstage

The vboot verification in a stage proper is unified
replacing duplicate code in the tegra SoC code. The
original verstage.c file is renamed to reflect its
real purpose. The support for a single verstage flow
is added to the vboot2 directory proper.

BUG=chrome-os-partner:44827
BRANCH=None
TEST=Built glados.

Change-Id: I14593e1fc69a1654fa27b512eb4b612395b94ce5
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/11744
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/src/vendorcode/google/chromeos/vboot_common.h b/src/vendorcode/google/chromeos/vboot_common.h
index f4d5e11..3a9c89b 100644
--- a/src/vendorcode/google/chromeos/vboot_common.h
+++ b/src/vendorcode/google/chromeos/vboot_common.h
@@ -48,4 +48,10 @@
 
 void vboot_reboot(void);
 
+/* Main logic for verified boot. verstage() is the stage entry point
+ * while the verstage_main() is just the core logic. */
+void verstage_main(void);
+void verstage_mainboard_init(void);
+void verstage(void);
+
 #endif /* VBOOT_COMMON_H */