safexcel: Fix the SHA-HMAC digest computation when AAD is present

The driver would fail to include the AAD in the input stream, resulting
in incorrect digests for requests combining SHA-HMAC with AES-CBC or
-CTR. Ensure that the AAD is included in the processor's input stream,
and fix the corresponding instruction sequence to include the AAD as
input to the digest computation.

This is a direct commit to stable/12 since the bug was introduced while
merging there and is not present in later branches.