crypto: x86/poly1305 - remove cra_alignmask

crypto_poly1305_final() no longer requires a cra_alignmask, and nothing
else in the x86 poly1305-simd implementation does either.  So remove the
cra_alignmask so that the crypto API does not have to unnecessarily
align the buffers.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>