Add a PERSO_AUTH appid to sign data passed through the
AUTH mn50.
Add a signer command to start and generate signatures.
Clean UART init to avoid spurious nonprinting characters
that will contaminate the siugnature.
BUG=b:36910757
BRANCH=None
TEST=generates signature for uart and spi
Signed-off-by: Nick Sanders <nsanders@chromium.org>
Change-Id: I5fc3c4ee34898421060b57b774a09734f6a1bae5
Reviewed-on: https://chromium-review.googlesource.com/670984
Reviewed-by: Marius Schilder <mschilder@chromium.org>