Add CSR generation script for signing PSP Verstage

This script is based on previous key generation scripts and on the
AMD document describing their recommendations.

BUG=b:166095736
TEST=Generate keys of different sizes with different passphrases in
various directories.

Change-Id: I76a31f5d592d233282c145a9a4ce5220a2d597d8
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2380612
Tested-by: Martin Roth <martinroth@google.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
1 file changed