Relax HMAC computation check

This KM4 key agreement check is causing some pain on early units
that aren't completely provisioned in both locked and non-Green
(unlocked) states.

This doesn't impact KM3 devices (Pixel 2016/2017 etc.)

Bug: 110301629
Change-Id: I5a737ac8a335863b1099c29cf3c0496adeb41e15