crypto: morus - Add generic MORUS AEAD implementations

This patch adds the generic implementation of the MORUS family of AEAD
algorithms (MORUS-640 and MORUS-1280). The original authors of MORUS
are Hongjun Wu and Tao Huang.

At the time of writing, MORUS is one of the finalists in CAESAR, an
open competition intended to select a portfolio of alternatives to
the problematic AES-GCM:

https://competitions.cr.yp.to/caesar-submissions.html
https://competitions.cr.yp.to/round3/morusv2.pdf



Signed-off-by: Ondrej Mosnacek <omosnacek@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>