crypto: octeontx2 - set assoclen in aead_do_fallback()

Currently, in case of aead fallback, no associated data info is set in the
fallback request. To fix this, call aead_request_set_ad() to pass the assoclen.

Fixes: 6f03f0e8 ("crypto: octeontx2 - register with linux crypto framework")
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>