fpsensor: add user_id to key derivation
fpsensor: add user_id to key derivation

Derive the key with HKDF, with 1 expand step to add the user_id to the
key derivation process. This requires that the size of user_id is
exactly SHA256_DIGEST_SIZE, which is enforced by a BUILD_ASSERT().
Also bump the template format to 2.

BRANCH=nocturne
BUG=b:116875889
BUG=b:73337313
TEST=enroll/unlock works as expected
TEST=templates with format version 1 are rejected
TEST=manually copy v2 templates between a user and another one. biod
attempts to load them and they are rejected by the fpcmu as expected.

Change-Id: Ie72d7c6233acb1d7e077599181b3848773783364
Signed-off-by: Nicolas Norvez <3001a977f47a2bc94ec05551872e2ce88b323556@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1252458
Reviewed-by: Adam Langley <db68fba232b2c49ed3e9d3081df349dde7b61dfd@chromium.org>
Reviewed-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec