vboot2: Add prototype for hwcrypto RSA Introduce new prototype for HW RSA accleration. This is not used on anywhere yet but will unblock coreboot work to support HW RSA. BRANCH=none BUG=b:163710320, b:161205813 TEST=make runtests; emerge-zork coreboot depthcharge Change-Id: Ic4b93f32410efdd06bd012efe58749b6ef0692c6 Signed-off-by: Kangheui Won <[email protected]> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2364338 Reviewed-by: Julius Werner <[email protected]>