Revert "crypto: powerpc/poly1305 - Add SIMD fallback"

This reverts commit c66d7ebb.

Link: https://lore.kernel.org/all/02c22854-eebf-4ad1-b89e-8c2b65ab8236@csgroup.eu/


Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>