[dif, hmac] Add unittest for hmac process function
[dif, hmac] Add unittest for hmac process function

Signed-off-by: Douglas Reis <df95399f7253aef5711aa5e1f53e8824981313ab@lowrisc.org>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan