Changed VerifyFirmwarePreamble to check for a valid kernel_subkey_sign_algorithm from the preamble.
Originally, an incorrect kernel_subkey_sign_algorithm wouldn't be detected and could cause the RSA
verification to read past the end of a buffer.
Review URL: http://codereview.chromium.org/2837002
Patch from Axel Hansen <axelrh@google.com>.
This creates a new vboot_firmware subdirectory, and which contains the
entirety of the BIOS code. There shouldn't be anything in this directory
that is NOT required by the BIOS.
Review URL: http://codereview.chromium.org/2219004
