Convert the x86 implementations of MORUS-1280 to use the AEAD SIMD
helpers, rather than hand-rolling the same functionality.  This
simplifies the code and also fixes the bug where the user-provided
aead_request is modified.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>