vboot2: use hwcrypto for RSA when allowed

Add vb2ex_hwcrypto_rsa_verify support for RSA verification.
If firmware implements the function it will used instead of SW
implementation in vboot.

Also separate hwcrypto stubs to 2stub_hwcrypto.c for depthcharge and coreboot.
Depthcharge needs stubs but fails to compile 2stub.c

BUG=b:163710320, b:161205813
TEST=make runtests
TEST=check hwcrypto is allowed/disallowed depending on nvmem flag

Change-Id: I85573e7cff31f32043db4b0a6b24b642856024e3
Signed-off-by: Kangheui Won <khwon@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2353775
Reviewed-by: Julius Werner <jwerner@chromium.org>
13 files changed