vboot: add and rejuggle Kconfig options

The ChromeOS machines employing vboot verfication require
different combinations of support:

1. When vboot verification starts.
2. Is the vboot code a separate stage or program?
3. If a separate stage, does the that vboot program (verstage) return
   to the stage that loaded the verstage?

For the above, #1 is dependent on when to load/run vboot logic which
is orthogonal to #2. However, #3 is dependent on #2. The logic
to act on the combinations follows in subsequent patches.

Change-Id: I39ef7a7c2858e7de43aa99c38121e85a57f1f2f6
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/10024
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
3 files changed